Ice machine makes little or no ice, or will not harvest

Troubleshooting · Applies to: Ice machine

Too little ice or ice that stays on the plate: water supply and pressure, condenser and room, harvest, ice pattern, leaking hot gas or water valves and scale.

Last checked: October 25, 2026 Field mode: large buttons, questions first and the screen kept on.

A cube ice machine works in cycles. In the freeze cycle the water pump runs water over the cold evaporator plate until the ice is thick enough; then the harvest starts: the hot gas valve sends warm discharge gas into the evaporator, the ice comes loose and drops into the bin, and the water inlet valve refills the sump. Flake and nugget machines freeze all the time in a cylinder with an auger. The ice machine manufacturers each have their own diagnosis tables for long freeze, long harvest and low production, and the same few causes come back: the water supply, the condenser and the room, scale, and heat that leaks into the freeze cycle ^[1]^[2]^[3]. Ice is food: clean and sanitise the water system after any work, following the manufacturer's instructions.

Work on the refrigerant circuit may only be carried out by certified personnel. Isolate the power before working on electrical parts and take particular care with high pressures (CO2) and flammable refrigerants (A2L and A3). Always follow the manufacturer's instructions.

Confirm the fault first

Find out what the customer means: less ice than before, no ice at all, or ice that stays on the plate. Read any fault code or lamp on the controller and check that the bin is not simply full or the bin switch held. Then follow one whole cycle with a watch: time the freeze and the harvest and compare them with the times for the model in the service manual, check that the sump fills, and look at the ice on the plate just before the harvest.

📏 Measurement guide: calculate superheat and subcooling 🔢 Alarm and fault codes

Flowchart

Causes, most likely first

The order is approximate and based on common faults in the field. Always measure before replacing anything.

1
Flowchart B
The condenser cannot get rid of the heat: a dirty condenser, blocked air flow or a hot room, a fan pressure control that cycles the fans at too low a pressure, or too little or too warm cooling water. A room that is too cold also stops production: some air-cooled cubers stop as if the bin were full (Scotsman BC0530: below about 10 °C) ^[5]^[6]^[7].
Remedy: Clean the condenser and the air filter, give the machine the clearances in the manual, check the fan cut-in pressure and the cooling water against the specification, and move the machine or change the room if it is outside the permitted range.
🛠 How do I do it? Step by step
Only qualified personnel may work on refrigeration and electrical systems. Follow the manufacturer's manual and local rules; the steps are guidance, not a replacement for training.
Clean a condenser or gas cooler
A dirty condenser or gas cooler raises the condensing pressure, the power consumption and the risk of high pressure trips. Clean it, straighten the fins and check that air can flow freely.
1. Measure before you clean. With the system running, note the condensing pressure (or gas cooler outlet temperature on CO2) and the air-on temperature, so that you can see the effect afterwards.
  ✓ Check: Pressure and air temperature are recorded.
2. Isolate and lock off. Isolate the condensing unit and fans, lock and tag the isolator and prove dead at the fan motor terminals. Fans can otherwise start automatically. On roofs, use fall protection.
  ✓ Check: 0 V at the fan terminals and the fans have stopped.
3. Remove loose dirt. Brush off leaves and fluff from the air-entering side with a soft brush along the fins. Blow or rinse from the air-leaving side, against the normal airflow, so dirt is pushed out rather than in.
  ✓ Check: The surface of the coil is free of loose dirt.
4. Clean with coil cleaner and water. Protect fan motors and electrical parts from water. Apply a coil cleaner suitable for the fin material, follow its safety data sheet (gloves and goggles) and rinse with low-pressure water against the normal airflow. Never use a high-pressure washer, which flattens the fins.
  ✓ Check: The rinse water runs clear and the fins are undamaged.
5. Straighten fins and check clearances. Straighten bent fins with a fin comb of the right pitch. Check that nothing blocks the air inlet or outlet and that warm air cannot recirculate to the inlet (walls, snow, other units).
  ✓ Check: Fins are straight and the free distances around the unit match the installation instructions.
6. Restart and compare. Remove your lock, restore power and let the system stabilise. Compare the condensing pressure and the air-on temperature with the values before cleaning.
  ✓ Check: The condensing temperature is lower at a similar air temperature.
Check head pressure control
Too low condensing pressure in winter starves the expansion valve; too high in summer costs energy and trips the HP switch. Check fan control, head pressure valves and water regulating valves against the setpoint.
1. Read the condensing pressure and setpoint. Connect a calibrated gauge to the discharge or liquid line port and note the condensing pressure setpoint and fan stages in the controller or speed controller. Never exceed the system PS.
  ✓ Check: You know the actual condensing pressure and the setpoint.
2. Check fan staging and speed control. Watch the fans as the pressure rises and falls: stages cut in and out, or the speed changes, around the setpoint. Measure the speed controller output if a fan does not respond.
  ✓ Check: Fans start, stop or change speed at the set pressures.
3. Check the fans with power off. If a fan does not run, isolate and lock off, check the fan motor and blades and that the coil is clean before blaming the control. Fans can start automatically.
  ✓ Check: Fans turn freely and the condenser is clean.
4. Check head pressure valves in cold weather. On systems with head pressure valves (e.g. Sporlan ORI/ORD or Danfoss KVR/NRD), check during low ambient that the bypass to the receiver gets warm when the valve regulates, and that there is enough refrigerant for the flooded condenser (winter charge, sight glass full).
  ✓ Check: The condensing pressure is held at the valve setting and the sight glass stays full in cold weather.
5. Check the water regulating valve. On water-cooled condensers, check that the water regulating valve opens more as the condensing pressure rises and closes at standstill. Compare water in and out temperatures.
  ✓ Check: The valve modulates and the condensing pressure is steady; no water flows at standstill.
6. CO2 gas coolers. On transcritical CO2 (R744) the high pressure is set by the high pressure valve and the gas cooler fans together; check it as described in the CO2 high pressure valve guide.
  ✓ Check: Gas cooler outlet temperature and high pressure follow the controller setpoints.
2
Flowchart F
Scale on the evaporator, the distributor or spray jets, or on the water level and ice thickness sensors: the freeze and the harvest get longer, the cubes come out white or half formed and the controller may lock out ^[3]^[14]^[15].
Remedy: Descale and sanitise with the cleaner the manufacturer approves, clean the sensors before replacing any parts and treat hard water (Wessamat, for example, asks for at most 10 °dH).
🛠 How do I do it? Step by step
Only qualified personnel may work on refrigeration and electrical systems. Follow the manufacturer's manual and local rules; the steps are guidance, not a replacement for training.
Descale and sanitise an ice machine
Scale on the evaporator and water system slows harvest and cuts capacity, and dirty water parts are a food hygiene risk. Descale and sanitise at the interval the manufacturer gives, more often with hard water.
1. Empty the bin and stop the machine. Stop ice production, discard all ice in the bin (it may be contaminated by the chemicals) and drain the water trough. Isolate, lock off and prove dead before removing panels or touching electrical parts.
  ✓ Check: The bin is empty, the trough is drained and the meter shows 0 V on the incoming terminals.
2. Check water hardness and choose the chemicals. Test the water hardness and read the manual for which descaler and sanitiser are approved for this evaporator (nickel-plated and stainless evaporators need different products). Wear gloves and goggles and read the safety data sheet. Never mix descaler and sanitiser.
  ✓ Check: You have the approved products, the mixing ratio from the manual or data sheet, and gloves and goggles on.
3. Run the descale cycle. Restore power and start the machine's clean or descale mode. Add the descaler to the trough in the amount the manual gives and let it circulate for the stated time.
  ✓ Check: The solution circulates over the whole evaporator and the scale loosens.
4. Clean removable parts by hand. Isolate again. Remove the water distribution tube, curtain, trough and sensors as the manual describes, soak them in descaler solution and brush them with a soft brush. Clean the water level and ice thickness sensors carefully so their readings are not upset.
  ✓ Check: All parts are free of scale and slime; no white deposits remain on the evaporator or the sensors.
5. Rinse and sanitise. Rinse everything with clean drinking water until no descaler is left. Refit the parts and run the sanitise cycle with an approved food-contact sanitiser (and wipe the bin and door with it), then rinse as the product instructions require.
  ✓ Check: The rinse water is clear and has no smell of chemicals; the sanitiser contact time has been kept.
6. Restart and discard the first ice. Put the machine back into ice-making mode. Discard the first batch or batches of ice as the manual says. Record the date and water hardness, and check the water treatment or filter if scale builds up quickly.
  ✓ Check: The machine harvests normally and the ice is clear, without taste or smell.
3
Flowchart A
Too little water reaches the machine: a closed tap, a blocked water filter or inlet strainer, too low dynamic pressure or an inlet valve that does not open, so the sump does not fill and the machine makes thin ice or stops on maximum fill time ^[4].
Remedy: Open the supply, replace the water filter, clean the inlet strainer and measure the dynamic pressure at the inlet valve while it fills; compare it with the manual. If the sump still does not fill, check the voltage on the inlet valve coil.
🛠 How do I do it? Step by step
Only qualified personnel may work on refrigeration and electrical systems. Follow the manufacturer's manual and local rules; the steps are guidance, not a replacement for training.
Check the ice machine water supply
Too low water pressure, a blocked filter or warm water gives thin or cloudy ice, long cycles and water alarms.
1. Check the supply connection. Check that the machine is connected to cold drinking water through its own shut-off valve and a backflow preventer as local rules require, and not to a hot or recirculated supply.
  ✓ Check: The supply is cold drinking water with a shut-off valve and backflow protection.
2. Measure the water pressure. Connect a water pressure gauge to the supply and read the pressure while the inlet valve fills.
  ✓ Check: The dynamic pressure is within the range in the manual (often about 1.4–5.5 bar, 20–80 psi).
3. Measure the water temperature. Measure the inlet water temperature with a thermometer.
  ✓ Check: The temperature is within the manufacturer's limits; warmer water reduces ice output.
4. Check the filter and inlet strainer. Close the supply and isolate the machine before opening water parts near electrical components. Check the filter cartridge's replacement date or pressure drop and clean the strainer at the inlet valve.
  ✓ Check: The strainer is clean and the filter cartridge is within its service life.
5. Check the inlet valve. Switch on and measure the voltage on the inlet valve coil when it should fill. Check that it closes tightly when the signal is off.
  ✓ Check: The coil gets its rated voltage, the trough fills in normal time and no water runs through when the valve is closed.
6. Flush and test. Flush the line after work on the filter, sanitise parts that were opened and let the machine run a full cycle.
  ✓ Check: The trough fills correctly and the machine makes full, clear ice.
4
Flowchart E
Heat leaks into the freeze cycle: the hot gas valve leaks through (its outlet is warm), the water inlet or purge valve lets water in during freeze, or hot water reaches the machine through a missing or faulty check valve in the building, often one shared with a dishwasher. The freeze gets long and the ice is often thick at the bottom of the plate ^[1]^[2]^[12]^[13].
Remedy: Replace a leaking hot gas valve, inlet valve or purge valve. Connect the machine to cold water only and fit or replace the check valve in the building supply.
🛠 How do I do it? Step by step
Only qualified personnel may work on refrigeration and electrical systems. Follow the manufacturer's manual and local rules; the steps are guidance, not a replacement for training.
Check the ice machine water supply
Too low water pressure, a blocked filter or warm water gives thin or cloudy ice, long cycles and water alarms.
1. Check the supply connection. Check that the machine is connected to cold drinking water through its own shut-off valve and a backflow preventer as local rules require, and not to a hot or recirculated supply.
  ✓ Check: The supply is cold drinking water with a shut-off valve and backflow protection.
2. Measure the water pressure. Connect a water pressure gauge to the supply and read the pressure while the inlet valve fills.
  ✓ Check: The dynamic pressure is within the range in the manual (often about 1.4–5.5 bar, 20–80 psi).
3. Measure the water temperature. Measure the inlet water temperature with a thermometer.
  ✓ Check: The temperature is within the manufacturer's limits; warmer water reduces ice output.
4. Check the filter and inlet strainer. Close the supply and isolate the machine before opening water parts near electrical components. Check the filter cartridge's replacement date or pressure drop and clean the strainer at the inlet valve.
  ✓ Check: The strainer is clean and the filter cartridge is within its service life.
5. Check the inlet valve. Switch on and measure the voltage on the inlet valve coil when it should fill. Check that it closes tightly when the signal is off.
  ✓ Check: The coil gets its rated voltage, the trough fills in normal time and no water runs through when the valve is closed.
6. Flush and test. Flush the line after work on the filter, sanitise parts that were opened and let the machine run a full cycle.
  ✓ Check: The trough fills correctly and the machine makes full, clear ice.
Check a solenoid valve (liquid line or hot gas)
A solenoid valve that does not open starves the evaporator (low pressure, warm room); one that does not close lets refrigerant through when it should not (pump-down fails, flooding, or hot gas leaking into the evaporator). Check the coil first, then the valve itself.
1. Find out whether the valve should be open. Read in the controller or the wiring diagram when the valve is energised (for example with cooling demand, during pump-down or during hot gas defrost). Compare with what the system does right now.
  ✓ Check: You know whether the valve should be open or closed at this moment.
2. Check that the coil gets voltage. Measure the voltage across the coil terminals when the valve should be open. Hold a steel screwdriver blade near (not touching) the top of the coil: a live coil pulls it slightly. Check that the coil voltage on its label matches the supply.
  ✓ Check: The coil has the rated voltage (label) when the valve should be open; if not, the fault is upstream: thermostat, controller output, contactor, fuse or wiring.
3. Check the coil itself. Isolate and lock off, prove dead, and disconnect the coil. Measure its resistance and compare with the manufacturer's value; look for a burnt smell, discolouration or a cracked coil. Make sure the coil is the right type for the valve body and sits fully down on the armature tube with its nut tight.
  ✓ Check: Coil resistance matches the data (an open circuit or a very low value means a faulty coil), and the coil is the right one and correctly fitted.
4. Check that the valve opens. With the coil energised and the system running, measure the temperature on both sides of the valve with clamp thermometers. An open valve has (almost) the same liquid temperature on both sides; a clear temperature drop or frost after the valve means it is not opening fully or is restricted. Check the flow direction arrow on the valve body.
  ✓ Check: Little or no temperature difference across the valve when it should be open, and it is fitted in the direction of the arrow.
5. Check that the valve closes. De-energise the coil (or let the controller close it) and watch what happens: on a pump-down system the suction pressure must fall and the compressor must stop on the low pressure switch and stay off; a hot gas valve must leave the line after it cool during the freeze or cooling cycle.
  ✓ Check: The system pumps down and stays down, or the line after a hot gas valve stays cool; a valve that leaks through must be repaired or replaced.
6. Repair or replace. A faulty coil can be changed without opening the circuit. If the valve body leaks or sticks, opening the circuit is work for certified personnel: recover the refrigerant, replace the valve (or its internal parts) with nitrogen flowing while brazing, pressure test with dry nitrogen, evacuate and charge by weight. Protect the valve from heat while brazing as the manufacturer describes.
  ✓ Check: The valve opens and closes as it should, there is no leak at the new joints, and the work is recorded in the logbook where the refrigerant rules require it.
5
Flowchart C
The harvest does not work: the hot gas valve does not open (no coil voltage or a burnt coil), too little hot gas (wrong charge, or the condenser fan runs during the harvest), an ice bridge that is too thick, a machine that is not level, or an evaporator surface that holds the ice (scale, worn plating or a missing seal) ^[8]^[9].
Remedy: During the harvest, measure the coil voltage and resistance of the hot gas valve and check that the suction pressure rises. Check the discharge temperature at the start of the harvest and that the condenser fan stops, level the machine, set the bridge thickness and descale the evaporator; replace it if the plating is worn.
🛠 How do I do it? Step by step
Only qualified personnel may work on refrigeration and electrical systems. Follow the manufacturer's manual and local rules; the steps are guidance, not a replacement for training.
Check ice machine harvest and ice thickness
When the harvest does not work the ice becomes too thick or too thin, sticks to the evaporator or freezes into one block. Check the thickness setting, the hot gas valve and the level of the machine.
1. Watch a full cycle. Remove the front panel and watch a freeze and harvest cycle. Note the time and the ice thickness at harvest. Live parts are exposed: keep hands out and use a CAT III/IV meter for measurements.
  ✓ Check: You know whether the fault is in the freeze, the start of harvest or the release.
2. Check the ice thickness. Measure the ice bridge between cubes and compare with the manual (on many cube machines about 3 mm). Adjust the thickness probe gap with a feeler gauge as the manual describes and clean the probe.
  ✓ Check: The bridge thickness is as the manual specifies on the next harvest.
3. Check the hot gas valve. During harvest, measure the voltage on the hot gas valve coil and watch the suction pressure on gauges. Beware of the hot discharge line.
  ✓ Check: The coil gets its rated voltage and the suction pressure rises clearly when harvest starts.
4. Check the harvest end. Check that the harvest ends when the ice falls (curtain switch, thermistor or timer, depending on the model) and that the ice falls off the whole evaporator.
  ✓ Check: All ice drops and the machine goes back to freezing without a long harvest time.
5. Level the machine. Put a spirit level on the machine in both directions and adjust the feet.
  ✓ Check: The machine is level in both directions and the ice is equally thick across the evaporator.
6. Clean the water distribution. Check the water distribution tube and plate for scale and clean them if water does not run evenly over the evaporator.
  ✓ Check: Water flows evenly over the whole evaporator and the cubes are fully formed.
Descale and sanitise an ice machine
Scale on the evaporator and water system slows harvest and cuts capacity, and dirty water parts are a food hygiene risk. Descale and sanitise at the interval the manufacturer gives, more often with hard water.
1. Empty the bin and stop the machine. Stop ice production, discard all ice in the bin (it may be contaminated by the chemicals) and drain the water trough. Isolate, lock off and prove dead before removing panels or touching electrical parts.
  ✓ Check: The bin is empty, the trough is drained and the meter shows 0 V on the incoming terminals.
2. Check water hardness and choose the chemicals. Test the water hardness and read the manual for which descaler and sanitiser are approved for this evaporator (nickel-plated and stainless evaporators need different products). Wear gloves and goggles and read the safety data sheet. Never mix descaler and sanitiser.
  ✓ Check: You have the approved products, the mixing ratio from the manual or data sheet, and gloves and goggles on.
3. Run the descale cycle. Restore power and start the machine's clean or descale mode. Add the descaler to the trough in the amount the manual gives and let it circulate for the stated time.
  ✓ Check: The solution circulates over the whole evaporator and the scale loosens.
4. Clean removable parts by hand. Isolate again. Remove the water distribution tube, curtain, trough and sensors as the manual describes, soak them in descaler solution and brush them with a soft brush. Clean the water level and ice thickness sensors carefully so their readings are not upset.
  ✓ Check: All parts are free of scale and slime; no white deposits remain on the evaporator or the sensors.
5. Rinse and sanitise. Rinse everything with clean drinking water until no descaler is left. Refit the parts and run the sanitise cycle with an approved food-contact sanitiser (and wipe the bin and door with it), then rinse as the product instructions require.
  ✓ Check: The rinse water is clear and has no smell of chemicals; the sanitiser contact time has been kept.
6. Restart and discard the first ice. Put the machine back into ice-making mode. Discard the first batch or batches of ice as the manual says. Record the date and water hardness, and check the water treatment or filter if scale builds up quickly.
  ✓ Check: The machine harvests normally and the ice is clear, without taste or smell.
Check a solenoid valve (liquid line or hot gas)
A solenoid valve that does not open starves the evaporator (low pressure, warm room); one that does not close lets refrigerant through when it should not (pump-down fails, flooding, or hot gas leaking into the evaporator). Check the coil first, then the valve itself.
1. Find out whether the valve should be open. Read in the controller or the wiring diagram when the valve is energised (for example with cooling demand, during pump-down or during hot gas defrost). Compare with what the system does right now.
  ✓ Check: You know whether the valve should be open or closed at this moment.
2. Check that the coil gets voltage. Measure the voltage across the coil terminals when the valve should be open. Hold a steel screwdriver blade near (not touching) the top of the coil: a live coil pulls it slightly. Check that the coil voltage on its label matches the supply.
  ✓ Check: The coil has the rated voltage (label) when the valve should be open; if not, the fault is upstream: thermostat, controller output, contactor, fuse or wiring.
3. Check the coil itself. Isolate and lock off, prove dead, and disconnect the coil. Measure its resistance and compare with the manufacturer's value; look for a burnt smell, discolouration or a cracked coil. Make sure the coil is the right type for the valve body and sits fully down on the armature tube with its nut tight.
  ✓ Check: Coil resistance matches the data (an open circuit or a very low value means a faulty coil), and the coil is the right one and correctly fitted.
4. Check that the valve opens. With the coil energised and the system running, measure the temperature on both sides of the valve with clamp thermometers. An open valve has (almost) the same liquid temperature on both sides; a clear temperature drop or frost after the valve means it is not opening fully or is restricted. Check the flow direction arrow on the valve body.
  ✓ Check: Little or no temperature difference across the valve when it should be open, and it is fitted in the direction of the arrow.
5. Check that the valve closes. De-energise the coil (or let the controller close it) and watch what happens: on a pump-down system the suction pressure must fall and the compressor must stop on the low pressure switch and stay off; a hot gas valve must leave the line after it cool during the freeze or cooling cycle.
  ✓ Check: The system pumps down and stays down, or the line after a hot gas valve stays cool; a valve that leaks through must be repaired or replaced.
6. Repair or replace. A faulty coil can be changed without opening the circuit. If the valve body leaks or sticks, opening the circuit is work for certified personnel: recover the refrigerant, replace the valve (or its internal parts) with nitrogen flowing while brazing, pressure test with dry nitrogen, evacuate and charge by weight. Protect the valve from heat while brazing as the manufacturer describes.
  ✓ Check: The valve opens and closes as it should, there is no leak at the new joints, and the work is recorded in the logbook where the refrigerant rules require it.
6
Flowchart D
Wrong refrigerant charge or superheat: ice that is thin or missing at the outlet end of the circuit points to too little refrigerant or high superheat; ice that freezes hard at the other end or into the water plate points to low superheat or overcharge ^[10]^[11].
Remedy: Measure superheat and subcooling in the middle of the freeze cycle. Leak test before adding refrigerant; if the charge is wrong, recover it and weigh in the amount on the data plate, and check or replace the expansion valve.
🛠 How do I do it? Step by step
Only qualified personnel may work on refrigeration and electrical systems. Follow the manufacturer's manual and local rules; the steps are guidance, not a replacement for training.
Measure superheat
Superheat shows whether the evaporator is fed with the right amount of refrigerant: too high starves the evaporator, too low risks liquid reaching the compressor. Measure at the evaporator outlet (for the expansion valve) and at the compressor (to protect it).
1. Let the system stabilise. Run at normal load for at least 10–15 minutes, not during or right after defrost. Wear goggles and gloves (cold pipes can cause frostbite); with A2L/A3 refrigerants keep ignition sources away.
  ✓ Check: Suction pressure and pipe temperature no longer drift.
2. Read the suction pressure. Connect the gauge to a port at the evaporator outlet if there is one; a port at the compressor shows a lower pressure because of the pressure drop in the suction line. Select the correct refrigerant.
  ✓ Check: The gauge shows a stable pressure, and you know where it was measured.
3. Measure the pipe temperature. Clamp a pipe thermometer on clean bare pipe next to the expansion valve bulb (evaporator superheat) and on the suction line about 15–30 cm before the compressor (compressor superheat), insulated from the surrounding air.
  ✓ Check: Both temperatures are stable.
4. Calculate superheat. Convert the pressure to the saturation temperature; for zeotropic blends use the dew point. Superheat = measured pipe temperature − saturation temperature.
  ✓ Check: The result is positive and is compared with the manufacturer's target; for a TXV at the evaporator outlet it is often around 5–8 K.
5. Interpret before adjusting. High superheat together with bubbles in the sight glass or low subcooling points to low charge or a restriction, not a valve setting. Very low compressor superheat means a risk of liquid floodback. Check charge, sight glass and filter drier before touching the valve.
  ✓ Check: The cause is supported by at least one other reading.
6. Adjust only when the cause is the valve. Adjust a TXV in small steps (about a quarter turn) and wait 15–20 minutes between steps; on an electronic valve change the setpoint in the controller. Record the values before and after.
  ✓ Check: Superheat settles at the target and stays stable during a full cycle.
Measure subcooling
Subcooling shows how much the liquid is cooled below its condensing temperature. Together with superheat it helps judge the charge and the condenser.
1. Run until stable. Let the system run at steady load for at least 15 minutes, not during or just after a defrost. Check that the condenser is clean and its fans run.
  ✓ Check: Pressures and temperatures are steady.
2. Measure the liquid pressure. Connect a gauge to the port at the condenser outlet or on the liquid line (see the guide on connecting gauges). Wear goggles and gloves.
  ✓ Check: You have a steady liquid pressure.
3. Measure the liquid temperature. Clamp a thermometer on clean pipe at the same place as the pressure reading and insulate the probe.
  ✓ Check: You have a steady pipe temperature from the same place.
4. Convert and calculate. Convert the pressure to saturation temperature for the refrigerant (bubble point for zeotropic blends). Subcooling = saturation temperature − measured liquid temperature.
  ✓ Check: You have a subcooling value in K.
5. Compare with the target. Compare with the manufacturer's target for the system. In systems with a receiver, subcooling at the receiver outlet is normally small and says little about the charge. On transcritical CO2 there is no subcooling on the high side; use the gas cooler outlet temperature and pressure instead.
  ✓ Check: You know whether the value is low, normal or high for this system type.
6. Interpret with care. Low subcooling with high superheat can mean too little refrigerant or a restriction; high subcooling with high condensing pressure can mean overcharge or non-condensables. Never add refrigerant to try: leak test first, repair, recover and weigh in the correct charge (F-gas certified personnel).
  ✓ Check: The conclusion is supported by superheat and pressures, not by subcooling alone.
Leak test a refrigeration system
Find leaks systematically, confirm the repair and record the work. Work that opens the refrigerant circuit requires F-gas certification (Regulation (EU) 2024/573 or national equivalent, EPA 608 in the USA).
1. Prepare the system and the detector. The system must be under pressure (running, or at standstill with warm ambient). Stop fans in the area to get calm air and ventilate low or enclosed spaces. With A2L/A3 refrigerants use no ignition sources and only detectors rated for them; with CO2 (R744) remember the very high pressure. Check the electronic detector (EN 14624) against its reference leak or as the manufacturer describes.
  ✓ Check: The detector reacts to the reference leak, and the air around the system is calm.
2. Search with the electronic detector. Move the probe slowly, a few centimetres per second, close to every brazed joint, flare, valve stem, Schrader core, gauge and coil bend. Refrigerants are heavier than air, so hold the probe at and below each joint. Follow the circuit in a fixed order so that nothing is missed.
  ✓ Check: Every joint along the circuit has been passed, and each alarm has been repeated at the same spot.
3. Confirm with bubble solution. Spray bubble leak solution on each suspected point and watch it for at least a minute; small leaks form bubbles or foam slowly.
  ✓ Check: Bubbles or foam pinpoint the leak, or the point is confirmed tight.
4. Use UV dye only where it is approved. If the system already contains a UV dye approved by the compressor manufacturer, light the joints with a UV lamp and wear UV glasses.
  ✓ Check: A fluorescent trace marks the leak, or no trace is visible.
5. Repair correctly. Recover the refrigerant (or isolate the section), repair with nitrogen flowing when brazing, pressure test with nitrogen, evacuate and charge by weight. Never top up refrigerant 'to test' without finding and repairing the leak.
  ✓ Check: The repaired joint holds the nitrogen test pressure and the system is charged with the specified amount.
6. Record and re-check. Write the leak location, cause, repair, refrigerant amount and your certificate number in the equipment logbook. Check the repair again within one month, as the F-gas regulation requires.
  ✓ Check: The logbook entry is complete and a follow-up check is booked.
Superheat and subcooling: how to measure and interpret them, including glide →
7
A dirty, grounded or wrongly set ice thickness sensor starts the harvest too early, and water level probes bridged by scale or moisture (often after cleaning) give a false level, so the machine does not fill, does not harvest or locks out ^[19]^[20].
Remedy: Clean and dry the sensors and the probe cap, and set the gap to the evaporator (bridge thickness) to the value in the manual.
🛠 How do I do it? Step by step
Only qualified personnel may work on refrigeration and electrical systems. Follow the manufacturer's manual and local rules; the steps are guidance, not a replacement for training.
Check ice machine harvest and ice thickness
When the harvest does not work the ice becomes too thick or too thin, sticks to the evaporator or freezes into one block. Check the thickness setting, the hot gas valve and the level of the machine.
1. Watch a full cycle. Remove the front panel and watch a freeze and harvest cycle. Note the time and the ice thickness at harvest. Live parts are exposed: keep hands out and use a CAT III/IV meter for measurements.
  ✓ Check: You know whether the fault is in the freeze, the start of harvest or the release.
2. Check the ice thickness. Measure the ice bridge between cubes and compare with the manual (on many cube machines about 3 mm). Adjust the thickness probe gap with a feeler gauge as the manual describes and clean the probe.
  ✓ Check: The bridge thickness is as the manual specifies on the next harvest.
3. Check the hot gas valve. During harvest, measure the voltage on the hot gas valve coil and watch the suction pressure on gauges. Beware of the hot discharge line.
  ✓ Check: The coil gets its rated voltage and the suction pressure rises clearly when harvest starts.
4. Check the harvest end. Check that the harvest ends when the ice falls (curtain switch, thermistor or timer, depending on the model) and that the ice falls off the whole evaporator.
  ✓ Check: All ice drops and the machine goes back to freezing without a long harvest time.
5. Level the machine. Put a spirit level on the machine in both directions and adjust the feet.
  ✓ Check: The machine is level in both directions and the ice is equally thick across the evaporator.
6. Clean the water distribution. Check the water distribution tube and plate for scale and clean them if water does not run evenly over the evaporator.
  ✓ Check: Water flows evenly over the whole evaporator and the cubes are fully formed.
8
Flake and nugget machines: the auger or gear motor overloads because of scale on the auger and evaporator, a liquid line valve that leaks at stop so the evaporator freezes solid, or a worn gear reducer or bearing ^[17]^[18].
Remedy: Descale the evaporator and auger, check that the liquid line valve closes tightly at stop, and check the gear reducer and the auger bearings.
🛠 How do I do it? Step by step
Only qualified personnel may work on refrigeration and electrical systems. Follow the manufacturer's manual and local rules; the steps are guidance, not a replacement for training.
Descale and sanitise an ice machine
Scale on the evaporator and water system slows harvest and cuts capacity, and dirty water parts are a food hygiene risk. Descale and sanitise at the interval the manufacturer gives, more often with hard water.
1. Empty the bin and stop the machine. Stop ice production, discard all ice in the bin (it may be contaminated by the chemicals) and drain the water trough. Isolate, lock off and prove dead before removing panels or touching electrical parts.
  ✓ Check: The bin is empty, the trough is drained and the meter shows 0 V on the incoming terminals.
2. Check water hardness and choose the chemicals. Test the water hardness and read the manual for which descaler and sanitiser are approved for this evaporator (nickel-plated and stainless evaporators need different products). Wear gloves and goggles and read the safety data sheet. Never mix descaler and sanitiser.
  ✓ Check: You have the approved products, the mixing ratio from the manual or data sheet, and gloves and goggles on.
3. Run the descale cycle. Restore power and start the machine's clean or descale mode. Add the descaler to the trough in the amount the manual gives and let it circulate for the stated time.
  ✓ Check: The solution circulates over the whole evaporator and the scale loosens.
4. Clean removable parts by hand. Isolate again. Remove the water distribution tube, curtain, trough and sensors as the manual describes, soak them in descaler solution and brush them with a soft brush. Clean the water level and ice thickness sensors carefully so their readings are not upset.
  ✓ Check: All parts are free of scale and slime; no white deposits remain on the evaporator or the sensors.
5. Rinse and sanitise. Rinse everything with clean drinking water until no descaler is left. Refit the parts and run the sanitise cycle with an approved food-contact sanitiser (and wipe the bin and door with it), then rinse as the product instructions require.
  ✓ Check: The rinse water is clear and has no smell of chemicals; the sanitiser contact time has been kept.
6. Restart and discard the first ice. Put the machine back into ice-making mode. Discard the first batch or batches of ice as the manual says. Record the date and water hardness, and check the water treatment or filter if scale builds up quickly.
  ✓ Check: The machine harvests normally and the ice is clear, without taste or smell.
Check a solenoid valve (liquid line or hot gas)
A solenoid valve that does not open starves the evaporator (low pressure, warm room); one that does not close lets refrigerant through when it should not (pump-down fails, flooding, or hot gas leaking into the evaporator). Check the coil first, then the valve itself.
1. Find out whether the valve should be open. Read in the controller or the wiring diagram when the valve is energised (for example with cooling demand, during pump-down or during hot gas defrost). Compare with what the system does right now.
  ✓ Check: You know whether the valve should be open or closed at this moment.
2. Check that the coil gets voltage. Measure the voltage across the coil terminals when the valve should be open. Hold a steel screwdriver blade near (not touching) the top of the coil: a live coil pulls it slightly. Check that the coil voltage on its label matches the supply.
  ✓ Check: The coil has the rated voltage (label) when the valve should be open; if not, the fault is upstream: thermostat, controller output, contactor, fuse or wiring.
3. Check the coil itself. Isolate and lock off, prove dead, and disconnect the coil. Measure its resistance and compare with the manufacturer's value; look for a burnt smell, discolouration or a cracked coil. Make sure the coil is the right type for the valve body and sits fully down on the armature tube with its nut tight.
  ✓ Check: Coil resistance matches the data (an open circuit or a very low value means a faulty coil), and the coil is the right one and correctly fitted.
4. Check that the valve opens. With the coil energised and the system running, measure the temperature on both sides of the valve with clamp thermometers. An open valve has (almost) the same liquid temperature on both sides; a clear temperature drop or frost after the valve means it is not opening fully or is restricted. Check the flow direction arrow on the valve body.
  ✓ Check: Little or no temperature difference across the valve when it should be open, and it is fitted in the direction of the arrow.
5. Check that the valve closes. De-energise the coil (or let the controller close it) and watch what happens: on a pump-down system the suction pressure must fall and the compressor must stop on the low pressure switch and stay off; a hot gas valve must leave the line after it cool during the freeze or cooling cycle.
  ✓ Check: The system pumps down and stays down, or the line after a hot gas valve stays cool; a valve that leaks through must be repaired or replaced.
6. Repair or replace. A faulty coil can be changed without opening the circuit. If the valve body leaks or sticks, opening the circuit is work for certified personnel: recover the refrigerant, replace the valve (or its internal parts) with nitrogen flowing while brazing, pressure test with dry nitrogen, evacuate and charge by weight. Protect the valve from heat while brazing as the manufacturer describes.
  ✓ Check: The valve opens and closes as it should, there is no leak at the new joints, and the work is recorded in the logbook where the refrigerant rules require it.
9
Flowchart G
The refrigeration circuit itself lacks capacity: a blocked filter drier or expansion valve, debris left in a remote system after installation, or a compressor that does not pump ^[16].
Remedy: Measure suction and discharge pressure and the compressor current. Clear the restriction and replace the filter drier (recover, evacuate and weigh in the charge), and test the compressor.
🛠 How do I do it? Step by step
Only qualified personnel may work on refrigeration and electrical systems. Follow the manufacturer's manual and local rules; the steps are guidance, not a replacement for training.
Connect gauges and read pressures
Correct pressures are the basis of almost every fault diagnosis. Connect the gauges so that no refrigerant is released and the reading can be trusted.
1. Choose gauges and protection. Check the refrigerant and the system PS on the nameplate. Choose gauges and hoses rated above PS and suitable for the refrigerant; CO2 needs at least 130 bar on the high side. Use tools rated for flammable refrigerants on A2L/A3 systems. Wear goggles and gloves.
  ✓ Check: Gauges and hoses are marked for the refrigerant and a pressure above the system PS.
2. Inspect hoses and couplers. Check hose seals and that the low-loss couplers are closed. Zero the digital manifold at atmospheric pressure.
  ✓ Check: Seals are intact, couplers closed and the gauges read zero when open to air.
3. Connect to the service ports. Remove the caps and fit the couplers to the suction port and the discharge or liquid port by hand, then open them. Keep away from ignition sources on A2L/A3 systems.
  ✓ Check: The couplers are tight and a leak detector finds nothing at the connections.
4. Remove air from the hoses. Evacuate the hoses with a vacuum pump, or use short low-loss hoses that do not need purging. Never purge hoses by blowing refrigerant to the air.
  ✓ Check: No air is in the hoses and no refrigerant has been released.
5. Read and convert. Read the pressures in stable operation and note whether they are gauge or absolute. Convert to saturation temperature for the right refrigerant: dew point for suction and bubble point for liquid with zeotropic blends. On CO2 above 31 °C / 73.8 bar (the critical point) there is no saturation temperature on the high side.
  ✓ Check: You have pressures and saturation temperatures for the correct refrigerant.
6. Disconnect without loss. Close the couplers, remove them and refit the caps, which are a secondary seal. Leak test the ports.
  ✓ Check: The caps are on and no leak is detected at the ports.
Replace a filter drier
Replace the filter drier after moisture, a compressor burnout, a restriction across the drier or whenever the circuit has been opened. Work on the refrigerant circuit requires F-gas certification; brazing is hot work.
1. Isolate or recover the refrigerant. Pump down or close valves to isolate the drier section where the system allows, otherwise recover the refrigerant with a recovery unit into a marked recovery cylinder. Break the vacuum with dry nitrogen to just above atmospheric pressure before opening. With A2L/A3 refrigerants purge with nitrogen and check with a gas detector.
  ✓ Check: The section reads slightly above 0 bar(g) on nitrogen and the pressure does not rise (no refrigerant left).
2. Choose the right drier. Use a drier of the same size or larger, with connections and capacity for the refrigerant. After a burnout or acid in the oil use a burnout (acid-removing) type and plan to replace it again after the clean-up; after moisture choose one with ample water capacity.
  ✓ Check: The new drier matches the refrigerant, size and situation, and its arrow follows the flow direction.
3. Cut out the old drier. Cut the pipes with a pipe cutter (never a hacksaw, which leaves filings) and deburr with the pipe end held downward. Keep the new drier capped until just before fitting.
  ✓ Check: Pipe ends are round, clean and burr-free.
4. Braze with nitrogen flowing. Get a fire permit, have an extinguisher at hand and remove flammable material. Purge a low flow of dry nitrogen through a regulator while brazing, and cool the drier body with a wet cloth so the desiccant is not overheated. Never use oxygen or compressed air. Flare driers are fitted with torque spanners instead.
  ✓ Check: Clean joints with full penetration, and no black oxide scale inside the pipe ends.
5. Pressure test with nitrogen. Pressurise with dry nitrogen through a regulator to the test pressure for the system, never above PS, and leak test the new joints.
  ✓ Check: The pressure holds and no leak is found at the joints.
6. Evacuate, charge and record. Evacuate with a micron gauge to the manufacturer's level (commonly below 500 micron/0.67 mbar), close off the pump and check that the vacuum holds. Charge the specified amount by weight and record the work and refrigerant amounts in the logbook.
  ✓ Check: The vacuum holds, the charge is weighed in and the logbook entry is complete.
Test whether the compressor pumps
Low pressure difference, low current and poor capacity can mean a worn compressor, but often the cause is a bypass elsewhere. Compare measurements with the manufacturer's data and rule out other causes before you condemn the compressor.
1. Measure in stable operation. Connect gauges to suction and discharge, and clamp thermometers on the suction line and on the discharge line close to the compressor, where the manufacturer specifies. Let the system run steadily for at least 15 minutes. Beware of the hot discharge pipe.
  ✓ Check: Pressures and temperatures are steady and noted together with the saturation temperatures.
2. Measure current and voltage. Measure the supply voltage and the current in each phase with a true-RMS clamp meter (CAT III/IV, insulated probes, no loose clothing).
  ✓ Check: You have voltage and current for all phases; the phases are balanced.
3. Compare with the compressor data. Enter the measured evaporating and condensing temperatures in the manufacturer's selection software or data sheet and read the expected current, capacity and discharge temperature.
  ✓ Check: Measured current and pressure difference are close to the data; clearly lower current at a low pressure difference suggests the compressor is not pumping.
4. Rule out bypasses. Check the hot gas bypass valve, unloaders or capacity control solenoids, a digital scroll valve and any reversing valve: a pipe that is hot where it should be cold shows gas leaking back to suction.
  ✓ Check: All bypass paths are closed when they should be; otherwise repair them first and measure again.
5. Check the internal relief valve. Many hermetic and scroll compressors have an internal pressure relief valve (IPR) between discharge and suction. If it has opened, suction pressure is high, discharge low, the shell is hot and the motor protection may trip. Find out why it opened (high pressure, blocked condenser) before restart.
  ✓ Check: The cause of an opened relief valve is found and removed, or the relief valve is ruled out.
6. Check the valves after stop (reciprocating). On a reciprocating compressor, watch the gauges right after it stops. Discharge pressure falling fast while suction rises points to leaking discharge valves. Do not run scroll compressors into deep vacuum to test them; it damages them.
  ✓ Check: Pressures equalise slowly; fast equalisation confirms leaking valves.
7. Decide. If the compressor still pumps too little with all other causes ruled out, plan a compressor replacement (see the guide on replacing a compressor). Record the measurements.
  ✓ Check: The decision is based on measurements compared with the manufacturer's data, and they are written down.
Continue with: Compressor runs but does not cool →
10
Remote condenser systems: the head pressure valve does not hold the minimum discharge pressure in freeze, the condenser bypass or vapour valve does not open at harvest, or a liquid inlet valve that stays closed lets the compressor pump down so no ice is made ^[22]^[23].
Remedy: Measure the pressures in freeze and harvest against the manual, check the coil voltage on each valve and replace the one that does not work.
🛠 How do I do it? Step by step
Only qualified personnel may work on refrigeration and electrical systems. Follow the manufacturer's manual and local rules; the steps are guidance, not a replacement for training.
Connect gauges and read pressures
Correct pressures are the basis of almost every fault diagnosis. Connect the gauges so that no refrigerant is released and the reading can be trusted.
1. Choose gauges and protection. Check the refrigerant and the system PS on the nameplate. Choose gauges and hoses rated above PS and suitable for the refrigerant; CO2 needs at least 130 bar on the high side. Use tools rated for flammable refrigerants on A2L/A3 systems. Wear goggles and gloves.
  ✓ Check: Gauges and hoses are marked for the refrigerant and a pressure above the system PS.
2. Inspect hoses and couplers. Check hose seals and that the low-loss couplers are closed. Zero the digital manifold at atmospheric pressure.
  ✓ Check: Seals are intact, couplers closed and the gauges read zero when open to air.
3. Connect to the service ports. Remove the caps and fit the couplers to the suction port and the discharge or liquid port by hand, then open them. Keep away from ignition sources on A2L/A3 systems.
  ✓ Check: The couplers are tight and a leak detector finds nothing at the connections.
4. Remove air from the hoses. Evacuate the hoses with a vacuum pump, or use short low-loss hoses that do not need purging. Never purge hoses by blowing refrigerant to the air.
  ✓ Check: No air is in the hoses and no refrigerant has been released.
5. Read and convert. Read the pressures in stable operation and note whether they are gauge or absolute. Convert to saturation temperature for the right refrigerant: dew point for suction and bubble point for liquid with zeotropic blends. On CO2 above 31 °C / 73.8 bar (the critical point) there is no saturation temperature on the high side.
  ✓ Check: You have pressures and saturation temperatures for the correct refrigerant.
6. Disconnect without loss. Close the couplers, remove them and refit the caps, which are a secondary seal. Leak test the ports.
  ✓ Check: The caps are on and no leak is detected at the ports.
Check a solenoid valve (liquid line or hot gas)
A solenoid valve that does not open starves the evaporator (low pressure, warm room); one that does not close lets refrigerant through when it should not (pump-down fails, flooding, or hot gas leaking into the evaporator). Check the coil first, then the valve itself.
1. Find out whether the valve should be open. Read in the controller or the wiring diagram when the valve is energised (for example with cooling demand, during pump-down or during hot gas defrost). Compare with what the system does right now.
  ✓ Check: You know whether the valve should be open or closed at this moment.
2. Check that the coil gets voltage. Measure the voltage across the coil terminals when the valve should be open. Hold a steel screwdriver blade near (not touching) the top of the coil: a live coil pulls it slightly. Check that the coil voltage on its label matches the supply.
  ✓ Check: The coil has the rated voltage (label) when the valve should be open; if not, the fault is upstream: thermostat, controller output, contactor, fuse or wiring.
3. Check the coil itself. Isolate and lock off, prove dead, and disconnect the coil. Measure its resistance and compare with the manufacturer's value; look for a burnt smell, discolouration or a cracked coil. Make sure the coil is the right type for the valve body and sits fully down on the armature tube with its nut tight.
  ✓ Check: Coil resistance matches the data (an open circuit or a very low value means a faulty coil), and the coil is the right one and correctly fitted.
4. Check that the valve opens. With the coil energised and the system running, measure the temperature on both sides of the valve with clamp thermometers. An open valve has (almost) the same liquid temperature on both sides; a clear temperature drop or frost after the valve means it is not opening fully or is restricted. Check the flow direction arrow on the valve body.
  ✓ Check: Little or no temperature difference across the valve when it should be open, and it is fitted in the direction of the arrow.
5. Check that the valve closes. De-energise the coil (or let the controller close it) and watch what happens: on a pump-down system the suction pressure must fall and the compressor must stop on the low pressure switch and stay off; a hot gas valve must leave the line after it cool during the freeze or cooling cycle.
  ✓ Check: The system pumps down and stays down, or the line after a hot gas valve stays cool; a valve that leaks through must be repaired or replaced.
6. Repair or replace. A faulty coil can be changed without opening the circuit. If the valve body leaks or sticks, opening the circuit is work for certified personnel: recover the refrigerant, replace the valve (or its internal parts) with nitrogen flowing while brazing, pressure test with dry nitrogen, evacuate and charge by weight. Protect the valve from heat while brazing as the manufacturer describes.
  ✓ Check: The valve opens and closes as it should, there is no leak at the new joints, and the work is recorded in the logbook where the refrigerant rules require it.
11
Ice stays frozen to the water plate: very cold supply water does not rinse off the ice residue after the harvest, or the ice web is too thick ^[24].
Remedy: Check the water temperature and the ice thickness setting, and clean the water plate.
🛠 How do I do it? Step by step
Only qualified personnel may work on refrigeration and electrical systems. Follow the manufacturer's manual and local rules; the steps are guidance, not a replacement for training.
Check ice machine harvest and ice thickness
When the harvest does not work the ice becomes too thick or too thin, sticks to the evaporator or freezes into one block. Check the thickness setting, the hot gas valve and the level of the machine.
1. Watch a full cycle. Remove the front panel and watch a freeze and harvest cycle. Note the time and the ice thickness at harvest. Live parts are exposed: keep hands out and use a CAT III/IV meter for measurements.
  ✓ Check: You know whether the fault is in the freeze, the start of harvest or the release.
2. Check the ice thickness. Measure the ice bridge between cubes and compare with the manual (on many cube machines about 3 mm). Adjust the thickness probe gap with a feeler gauge as the manual describes and clean the probe.
  ✓ Check: The bridge thickness is as the manual specifies on the next harvest.
3. Check the hot gas valve. During harvest, measure the voltage on the hot gas valve coil and watch the suction pressure on gauges. Beware of the hot discharge line.
  ✓ Check: The coil gets its rated voltage and the suction pressure rises clearly when harvest starts.
4. Check the harvest end. Check that the harvest ends when the ice falls (curtain switch, thermistor or timer, depending on the model) and that the ice falls off the whole evaporator.
  ✓ Check: All ice drops and the machine goes back to freezing without a long harvest time.
5. Level the machine. Put a spirit level on the machine in both directions and adjust the feet.
  ✓ Check: The machine is level in both directions and the ice is equally thick across the evaporator.
6. Clean the water distribution. Check the water distribution tube and plate for scale and clean them if water does not run evenly over the evaporator.
  ✓ Check: Water flows evenly over the whole evaporator and the cubes are fully formed.
12
Very pure water (reverse osmosis) is not detected by conductive water level sensing, so the controller reports that there is no water ^[21].
Remedy: Check the water treatment against the manufacturer's requirements for the model and adjust it so that the level sensing works.
🛠 How do I do it? Step by step
Only qualified personnel may work on refrigeration and electrical systems. Follow the manufacturer's manual and local rules; the steps are guidance, not a replacement for training.
Descale and sanitise an ice machine
Scale on the evaporator and water system slows harvest and cuts capacity, and dirty water parts are a food hygiene risk. Descale and sanitise at the interval the manufacturer gives, more often with hard water.
1. Empty the bin and stop the machine. Stop ice production, discard all ice in the bin (it may be contaminated by the chemicals) and drain the water trough. Isolate, lock off and prove dead before removing panels or touching electrical parts.
  ✓ Check: The bin is empty, the trough is drained and the meter shows 0 V on the incoming terminals.
2. Check water hardness and choose the chemicals. Test the water hardness and read the manual for which descaler and sanitiser are approved for this evaporator (nickel-plated and stainless evaporators need different products). Wear gloves and goggles and read the safety data sheet. Never mix descaler and sanitiser.
  ✓ Check: You have the approved products, the mixing ratio from the manual or data sheet, and gloves and goggles on.
3. Run the descale cycle. Restore power and start the machine's clean or descale mode. Add the descaler to the trough in the amount the manual gives and let it circulate for the stated time.
  ✓ Check: The solution circulates over the whole evaporator and the scale loosens.
4. Clean removable parts by hand. Isolate again. Remove the water distribution tube, curtain, trough and sensors as the manual describes, soak them in descaler solution and brush them with a soft brush. Clean the water level and ice thickness sensors carefully so their readings are not upset.
  ✓ Check: All parts are free of scale and slime; no white deposits remain on the evaporator or the sensors.
5. Rinse and sanitise. Rinse everything with clean drinking water until no descaler is left. Refit the parts and run the sanitise cycle with an approved food-contact sanitiser (and wipe the bin and door with it), then rinse as the product instructions require.
  ✓ Check: The rinse water is clear and has no smell of chemicals; the sanitiser contact time has been kept.
6. Restart and discard the first ice. Put the machine back into ice-making mode. Discard the first batch or batches of ice as the manual says. Record the date and water hardness, and check the water treatment or filter if scale builds up quickly.
  ✓ Check: The machine harvests normally and the ice is clear, without taste or smell.
13
Electrical fault: too low voltage under load, a worn contactor or a faulty control board, so the compressor or the valves do not work as they should.
Remedy: Measure the voltage under load against the data plate, check the contactor and the connections, and contact the manufacturer about board faults.
🛠 How do I do it? Step by step
Only qualified personnel may work on refrigeration and electrical systems. Follow the manufacturer's manual and local rules; the steps are guidance, not a replacement for training.
Measure voltage and current under load
Low voltage, phase imbalance or high current make motors overheat and trip. Measure at standstill, during start and in operation and compare with the nameplate. Live measurements in an open panel are for qualified personnel only.
1. Prepare for live measurement. Use a CAT III/IV multimeter with insulated probes and a true-RMS clamp meter with inrush function. Wear safety glasses, no loose clothing, and keep hands clear of fans and belts that can start automatically.
  ✓ Check: Meter and leads are CAT III or CAT IV rated and the meter works on a known source.
2. Measure the supply at standstill. Measure L1–L2, L2–L3 and L3–L1 (and phase to neutral where used) at the incoming terminals with the compressor stopped.
  ✓ Check: All voltages are within the range on the nameplate or data sheet (many compressors allow ±10 % of rated voltage).
3. Measure voltage during start and in operation. Measure the same phases at the compressor contactor while the compressor starts and again after a few minutes of running. A large drop during start points to a weak supply, undersized cables or a loose connection.
  ✓ Check: The voltage stays within the permitted range also during start and in operation.
4. Calculate the voltage imbalance. Imbalance (%) = largest deviation from the average of the three phase-to-phase voltages ÷ average × 100.
  ✓ Check: The imbalance is within the compressor manufacturer's limit (often about 2 %).
5. Measure the current on each phase. Clamp each phase conductor separately: the inrush current at start and the running current after the system has stabilised.
  ✓ Check: The running current does not exceed the rated load amps (RLA) on the nameplate and is about equal on all three phases.
6. Record and act. Write voltages, imbalance and currents in the service report. High voltage drop: tighten and check connections under isolation. Imbalance or high current: trace the supply or the motor before restarting repeatedly.
  ✓ Check: Readings are documented and any fault is traced to supply, connection or motor.
Test a contactor
Worn, welded or loosely connected contactor contacts cause single-phasing, overheating and motor damage. Check the contacts, the coil and the voltage drop, and replace a worn contactor. Electrical work is for qualified personnel only.
1. Isolate and lock off. Switch off and lock the isolator, attach a tag and prove dead with a two-pole voltage tester on all line and load terminals, also the coil supply, which can come from a separate control circuit.
  ✓ Check: 0 V on all poles, the coil terminals and to earth.
2. Inspect the contacts and the mechanism. Remove the arc cover if the design allows. Look for heavily pitted, burnt or welded contacts, and discoloured terminals or melted plastic. Press the armature by hand (power off) and check that it moves freely and springs back.
  ✓ Check: Contacts are without heavy pitting or welds, and the armature moves freely.
3. Check the coil. Disconnect one coil lead and measure the coil resistance. Compare with the manufacturer's data or a new contactor of the same type.
  ✓ Check: The coil is neither open (OL) nor near 0 Ω.
4. Check the coil voltage and pull-in. Reconnect, remove your lock, restore power and use the CAT III/IV meter to measure the voltage across the coil when the controller calls for operation.
  ✓ Check: The coil voltage matches the rating printed on the coil, and the contactor pulls in firmly without humming or chattering.
5. Measure the voltage drop across each pole. With the motor running, measure from line to load terminal across each closed pole.
  ✓ Check: The drop is close to 0 V and about equal on all poles; a pole with clearly higher drop has worn contacts.
6. Tighten or replace. Isolate and lock off again. Tighten all terminals to the manufacturer's torque. Replace a worn contactor with one of the same coil voltage and at least the same motor rating (AC-3), then restart and measure the current on each phase.
  ✓ Check: Terminals are tight, and the motor current is about equal on all phases after restart.

Checks from the manufacturers’ manuals (46)

Values and checks the manufacturers give for their own products; they apply to the product named.

True Ice (R-290): At the start of the harvest the discharge line about 15 cm (6 in) from the compressor should be at least about 60 °C (140 °F). If it is colder, check the charge, the expansion valve and non-condensables, and that the condenser fans stop during the harvest.^[25]
True Ice; Scotsman Eclipse (vapor inlet valve): Check the harvest valve coil: voltage during the harvest and resistance (True: 325–375 Ω). When the harvest starts the suction pressure should rise and the discharge pressure fall; if not, the valve does not open.^[26]
True Ice cubers: Check the supply first: water pressure about 1.4–6.9 bar (20–100 psi), cold water only, room about 2–43 °C and the rated voltage under load. A blocked water filter or low pressure gives long freeze times.^[27]
True Ice; Wessamat MicroCube; Scotsman: Dynamic water pressure at the inlet: True asks for 1.4–6.9 bar (20–100 psi), Wessamat at least 2 bar. Low pressure or a clogged inlet strainer or water filter gives slow filling and alarms on maximum fill time.^[4]
True Ice and Kold-Draft 60 series: Installation limits for air-cooled machines: True gives a room range of 1.7–43.3 °C and water pressure 1.4–6.9 bar; Kold-Draft wants at least 15 °C in the room and at least 0.34 bar dynamic pressure at the inlet valve.^[28]
Hoshizaki KM; Scotsman BC0530; Wessamat CubeLine: Site limits: Hoshizaki allows about 7–38 °C ambient; Scotsman wants at least 15 °C for air-cooled models and at least 0.34 bar (5 psi) dynamic water pressure at the inlet valve, and below about 10 °C its bin control acts as if the bin were full.^[29]
Scotsman BC0530; True Ice: Read the ice pattern on the evaporator: thin ice or large dimples at the outlet end of the circuit mean low charge or high superheat; ice that freezes hard at the other end, or into the water plate, means low superheat. Full, even sheets are the goal.^[11]
Scotsman BC0530: Water-cooled ice machines: subcooling above about 11 K in the middle of the freeze cycle means the circuit is overcharged; recover the charge and weigh in the amount on the data plate.^[30]
ITV MR 400; Scotsman Prodigy Eclipse: Harvest problems: during the harvest the low-side pressure must rise, the hot gas valve coil must have voltage and water should come in. ITV sets the maximum harvest to about 5 minutes and the harvest assist pump to more than 30 seconds.^[31]
Scotsman Prodigy Eclipse / EH222 with remote condensing unit: Remote condenser cubers: the head pressure valve must hold a minimum discharge pressure during freeze (Prodigy Eclipse with R404A about 217 psig, roughly 15 bar g), and the condenser bypass and vapour valves must open at the harvest; a slow harvest or no pressure rise on the low side points to these valves.^[22]
Scotsman Eclipse and Prodigy EH130 remote cubers: Remote cubers with a liquid inlet valve: if the valve does not open, the compressor pumps down and the suction pressure is very low, so no ice is made. During the harvest the low-side pressure must rise; if it does not while the vapour valve has voltage, that valve is faulty.^[23]
ITV IQN/IQF: Flake and nugget machines: a low-speed alarm on the gear motor means overload from scale on the auger and evaporator; a high-speed alarm means that no ice is being made, so check the refrigeration system.^[32]
NTF SL cube ice makers: In spray-type cubers an overflow standpipe in the sump that is not seated or sits in the wrong position lets the water run straight to drain, so the sump stays empty and no ice forms.^[33]
NTF SL cube ice makers: The spray system delivers no water: a clogged filter on the pump suction, scale inside the pump hoses, blocked nozzles, or a pump that does not run (failed run capacitor, seized rotor, open winding, or the timer micro-switch contact that feeds it).^[34]
NTF SL cube ice makers: If the pump gurgles or draws air during the freeze, the sump was not refilled in the harvest: check the supply pressure, the inlet valve coil, and that the cam timer actually powers the inlet valve during the harvest.^[35]
NTF SL cube ice makers: In these machines the inlet water also flows over the evaporator during the harvest to help release the cubes. Nominal valve flow to the evaporator is about 0.5 l/min (SL35–60), 0.8 l/min (SL70), 1.2 l/min (SL90–110), 1.2–2.5 l/min (SL140–260) and 2.5–3 l/min (SL280–350); time it into a jug, as low flow gives a slow, incomplete harvest and a low sump.^[36]
NTF SL cube ice makers: Electromechanical cubers: the cam timer only starts timing the freeze once the evaporator thermostat sees a cold plate. A faulty or misadjusted evaporator thermostat, or a refrigerant shortage that keeps the plate too warm, makes the freeze run on and on; a locked timer or a thermostat that does not switch back leaves the machine stuck in harvest, often with a sheet of ice under the evaporator.^[37]
NTF cube ice makers: Setting a replacement evaporator thermostat (NTF part 23591): turn the spindle fully clockwise, then back counter-clockwise by the model value – CM 90° (scale 5), SL and IC/IW/FRM/DSS 135° (scale 4), CVC 180° (scale 3). Clockwise gives thicker cubes; adjust in steps of about 10°. The sensing end of the capillary must touch the evaporator or the bulb well.^[38]
NTF ice makers: The bin thermostat stops the machine when its bulb gets cold; a room below about 7 °C does the same, so the machine stops as if the bin were full. Setting from fully clockwise: SL, IC/IW/FRM/DSS, IFT, SLF/SLT and CV1650 90° back (scale 5), CM and CV 135° (scale 4), CVC 45° (scale 6), GM 180° (scale 3). SL cubers only stop for a full bin at the end of a harvest.^[39]
NTF SL cube ice makers: The SL freeze time is set by a cam timer chosen for model, supply and cube size (for example 10 min for small, 12 min medium, 15 min large and 18 min extra-large cubes on most 220–240 V/50 Hz models). After a timer replacement, check that the new part number matches the table; the wrong timer gives thin or overgrown cubes and lower output.^[40]
NTF SL cube ice makers, water-cooled: Water-cooled cubers: if the condenser water valve does not close in the harvest, the condenser stays cold and too little hot gas reaches the evaporator, so the harvest is slow or incomplete. A failed suppression capacitor wired across the condenser pressure switch can keep the valve powered.^[41]
NTF SL cube ice makers: Ice output drops because the bin is flooded: a blocked or badly connected bin drain lets melt water stand in the bin and melt the ice.^[42]
NTF SL cube ice makers: Read the suction pressure at the compressor service valve at the start of the freeze and convert it to evaporating temperature. NTF gives a value per model and per air or water temperature; for air-cooled SL models it is roughly −16 to −8 °C, colder in a cooler room, and for water-cooled ones roughly −12 to −2 °C. A clearly higher value points to hot gas or water leaking in, or a compressor that does not pump.^[43]
NTF SL cube ice makers: The cups of spray-type evaporators are tin-plated copper: descale them with an approved cleaner and do not scrub or scrape, as a roughened surface holds the ice and slows the harvest.^[44]
NTF SL cube ice makers: Cubes come out irregular, cloudy or half formed when the spray nozzles are dirty or not aimed at the middle of the cups, or when the water is very hard.^[45]
NTF SLF and GM flake/granular ice makers: Flake and granular machines stop through safety devices wired in series with the gear motor: a float switch that opens when the water basin is empty, an evaporator thermostat (SLF) or an auto-reset evaporator pressure switch (GM) that trips when the evaporating temperature gets too low, for example from a refrigerant leak or broken gear motor teeth, a full-bin switch in the ice chute, and an auto-reset high pressure switch. A centrifugal switch on the gear motor also drops the compressor relay if the gear motor fails.^[46]
NTF GM granular ice makers: GM granular machines start the gear motor at once but the compressor only after a delay timer has run (about 8–10 minutes; its lamp blinks meanwhile). Switching the machine off and on restarts the delay, so wait it out before deciding that the compressor will not start.^[47]
Automatic ice cube makers with cam timer and spray system (ABM, probably NTF SL type): Cam-timer spray cubers: if the pump does not spray when the machine is started (for example during cleaning or a test), the timer is in its DEFROST (harvest) segment. Remove the front panel and turn the timer adjusting screw clockwise with a flat screwdriver until the pointer leaves the DEFROST zone; the pump should then run and spray.^[48]
Automatic ice cube makers with spray system (ABM, probably NTF SL type): After cleaning a spray cuber check that every part is back: the overflow tube, the pump filters, the spray bar with both end plugs and the hose from the pump to the spray bar, and that the holes in the bottom of the evaporator are clear. Do not bend the evaporator coils, pull off the water inlet hoses or remove the evaporator thermostat while cleaning.^[49]
Automatic ice cube maker, 21 kg/day model (ABM, probably NTF SL type): On the 21 kg/day cube maker the pump filter is not in the sump: it sits behind a threaded locking ring at the pump hose connection, and the pump stands to the right of the evaporator behind the rear panel. A blocked filter there stops the spray.^[50]
Automatic ice cube makers with spray system (ABM, probably NTF SL type): Descale this cuber with about 25 % white vinegar in water, at least once a month and more often with hard water, a warm room or heavy use. Corrosive descalers damage the machine's materials and void the warranty; loosen deposits on the evaporator with a soft brush and a non-abrasive sponge.^[51]
NTF linear (auger) granular ice makers, G series (G160, G280, G510, G1000): NTF G-series TB models have an evaporator safety thermostat on the suction line that stops the machine when the suction temperature reaches about −27 °C and lets it restart automatically at about +4 °C. A trip points to low refrigerant charge or poor water supply to the evaporator.^[52]
NTF linear (auger) granular ice makers, G series (G160, G280, G510, G1000): NTF G-series rotation sensor LED: off means a safety device in the series chain is open; orange blinking is the 8-minute start delay with the gear motor turning; orange steady is normal production; red blinking means the auger speed was outside about 4–13 rpm; red steady is a lock-out after 8 consecutive faults, reset by switching the power off and on.^[53]
NTF linear (auger) granular ice makers, G series (G160, G280, G510, G1000): NTF G-series auger machines: grey or dirty ice comes from worn bearings inside the evaporator; replace the bearings. When refitting the auger, tighten its fixing screw with a torque screwdriver to 40 Nm on GB and G160 models and 80 Nm on G280 and G500 models.^[54]
NTF GM600/GM1200 granular and MGT560/MGT900 pebble ice makers: NTF GM600/GM1200 and MGT560/MGT900: after the 10-minute stand-by the rotation sensor powers the compressor contactor and watches the auger. If the auger stops or slows down it drops the contactor for about 10 minutes and tries again; if the fault is still there it cuts the compressor for good. Remove the cause, then switch the machine off and on.^[55]
NTF SM flat flake ice makers (SM500–SM11000): NTF SM flakers: NTF gives evaporating and condensing temperatures per model and compressor at six increasing room or water temperatures. Evaporating temperatures lie between about −27.5 °C and −18 °C (for example SM500 A from about −24 °C to −19 °C); condensing about 33–56 °C air-cooled and about 42–45 °C water-cooled. A clearly warmer evaporator points to low charge or poor water spray.^[56]
NTF SM flat flake ice makers (SM500–SM11000): NTF SM flakers: when the ice level reaches the evaporator chamber the safety thermostat should stop the machine; if it does not, check the thermostat setting and that its probe sits fully in the bulb holder. As a back-up, rising ice pushes a transparent shield onto a safety microswitch outside the chamber, which stops the machine and resets by itself.^[57]
NTF SM flat flake ice makers (SM500–SM11000): NTF SM flakers: poor flake ice and low output come from too little water on the evaporator (float valve in the pump basin, clogged inlet connector filter, pump filter or scaled sprayer ring holes) or from low refrigerant charge.^[58]
NTF SM flat flake ice makers (SM500–SM11000): NTF SM flakers: during ice production an air-cooled SM drains no water at all, and a water-cooled one drains only the condenser water. Any other water at the drain points to the float valve in the pump basin, loose hose clamps or a blocked drain connector.^[59]
NTF IFT hollow cube ice makers (IFT55–IFT165): NTF IFT hollow cube makers: check the charge by the evaporating temperature. NTF gives a value per model, compressor and air or water temperature (+10 to +30 °C), roughly −10.5 °C to +0.5 °C (for example IFT55A with AEZ4425Z about −5.5 °C at 10 °C and 0 °C at 30 °C), and states that by the end of each production cycle the evaporating temperature must have come down to −15/−16 °C.^[60]
NTF IFT hollow cube ice makers (IFT55–IFT165): NTF IFT hollow cube makers run on R404A with small charges that must be weighed in, from about 170 g (IFT55W) to 480 g (IFT165A); air-cooled versions take more than water-cooled ones (for example IFT65A 270 g, IFT65W 240 g).^[61]
NTF IFT hollow cube ice makers (IFT55–IFT165): NTF IFT harvest: when the ice on the fingers stops the paddles, the paddle gear motor presses a micro-switch that energises the relay; the hot gas valve opens and the basin tips down. A capacitor on the overturning gear motor is needed to reverse it; if it fails the basin does not change direction. Separate micro-switches give the defrost start pulse, reverse the basin and stop it on its way up; do not overtighten their fixing screws.^[62]
NTF IFT hollow cube ice makers (IFT55–IFT165): NTF IFT cube size: a correct finger cube is about 4.2 ±0.3 cm long and 2.9 ±0.1 cm across. Thickness is set by the position of the paddles between the evaporator fingers (adjusted with a key, leaving a small clearance), because the harvest starts when the growing ice stops the paddles.^[63]
NTF IFT hollow cube ice makers (IFT55–IFT165): NTF IFT water level: the basin level is set with a screw (clockwise raises it), at most 3/4 turn either way, and only with the basin fully open so the trap is out of the water. The siphons in the line keep water out of the water level pressure switch; water there gives a wrong level.^[64]
NTF IFT hollow cube ice makers (IFT55–IFT165): NTF IFT: if the bin thermostat fails, ice keeps piling up in the bin until it blocks the basin from opening, and the harvest cannot finish. The cube slide must also move freely so that all cubes drop when the basin opens.^[65]
NTF IFT hollow cube ice makers (IFT55–IFT165): NTF IFT water inlet valves: the evaporator valve opens only during the harvest to refill the basin until the level pressure switch closes it. Rated flows are 1.2 (IFT55) and 2.5 (IFT65–IFT165), and the condenser valve on water-cooled models 1.2 (IFT55W) or 0.8 (IFT65–165W), probably in l/min; a slow valve leaves the basin low for the next freeze.^[66]

📝 Fill in a service report

Terms in this article

Superheat Subcooling Expansion valve Filter drier

Sources

Scotsman – CU1526/CU2026/CU3030 Service Manual (May 2008); Scotsman – Prodigy EH130 production/service manual (Apr 2008); True Manufacturing – Manuel de service après-vente True Ice, Réf 857284 TEC_TM_266 Rev. A (2024-04-05), CU: Service Diagnosis p. 29; EH130: p. 41; True: p. 65
Hoshizaki – Service manual KM-1100MAJ(50) + Scotsman – Manual Prodigy Eclipse 1200–2000 (August 2008) + ITV – MR 400 Troubleshooting guide, KM p. 25; Prodigy p. 41; MR 400 Long pre cooling
Hoshizaki – Service manual KM-1100MAJ(50) + ITV – Technical manual IQN/IQF flake and nugget ice machines (ES) + ITV – Technical manual NG series (ES), KM pp. 23-25; IQN/IQF pp. 42, 48-49; NG p. 29
True Manufacturing – True Ice service manual TEC_TM_198 Rev. A (03/2024) + Wessamat – MicroCube M120–M800 operating manual DE/EN (2023-04-17) + Scotsman – BC0530 service manual (March 2020), True p. 64; Wessamat p. 23 (EN p. 105); Scotsman BC0530 p. 38
Scotsman – CU1526/CU2026/CU3030 Service Manual (May 2008), Service Diagnosis – Low ice making capacity, p. 31
Scotsman – Prodigy Series modular cuber technical service manual (Jan 2015), p. 45
Scotsman – BC0530 service manual (March 2020) + ITV – IQN/IQF 90 (R290) technical manual (Spanish), Scotsman p. 35; ITV p. 48
True Manufacturing – True Ice service manual TEC_TM_198 Rev. A (03/2024) + Scotsman – Prodigy Series modular cuber technical service manual (Jan 2015), True p. 69; Scotsman p. 44
True Manufacturing – True Ice service manual TEC_TM_198 Rev. A (03/2024), pp. 65 and 69
Scotsman – Prodigy Eclipse 600/800/1000 Service Manual (Feb 2008) + ITV – Pulsar R290 technical manual (Spanish), Service Diagnosis, Low capacity and Poor ice formation, p. 46; Guía de resolución de problemas, p. 29
Scotsman – BC0530 service manual (March 2020) + True Manufacturing – True Ice service manual TEC_TM_198 Rev. A (03/2024), Scotsman p. 40; True p. 67 (E26/E32)
Scotsman – CU1526/CU2026/CU3030 Service Manual (May 2008); True Manufacturing – Manuel de service après-vente True Ice, Réf 857284 TEC_TM_266 Rev. A (2024-04-05), CU: Service Diagnosis p. 28 and 31; True: p. 64
Scotsman – Prodigy Series modular cuber technical service manual (Jan 2015) + Scotsman – Eclipse 1300/1600 remote low side cuber manual (Sept 2003), Prodigy p. 43; Eclipse p. 42
Scotsman – Prodigy Eclipse 600/800/1000 Service Manual (Feb 2008) + Scotsman – SRC065 Service Manual (Jan 2026) + True Manufacturing – True Ice service manual (Spanish) TEC_TM_265 Rev. A, P#857284 (2025-08-27), Service Diagnosis, p. 44–45; Service Diagnosis, p. 26; recolección prolongada, p. 65
Wessamat – MicroCube M120–M800 operating manual DE/EN (2023-04-17) + ITV – IQN/IQF 90 (R290) technical manual (Spanish) + Scotsman – Remote low side flaked/nugget ice machines service manual F1222L–N1322L (Dec 2014) + True Manufacturing – True Ice service manual TEC_TM_198 Rev. A (03/2024), Wessamat p. 23 (EN p. 105); ITV pp. 46–48; Scotsman p. 25; True p. 65
Scotsman – Prodigy Series modular cuber technical service manual (Jan 2015), p. 49
Scotsman – Prodigy N0422–F1522 Air, Water or Remote Service Manual (Dec 2014 / May 2017), Service Diagnosis – Remote Air Cooled, p. 42–43
Scotsman – Remote low side flaked/nugget ice machines service manual F1222L–N1322L (Dec 2014) + ITV – IQN/IQF 90 (R290) technical manual (Spanish), Scotsman p. 25; ITV p. 46
Scotsman – Prodigy Series modular cuber technical service manual (Jan 2015), pp. 44 and 52
Scotsman – Service manual BC0530 (March 2020) + Wessamat – Betriebsanleitung CubeLine DE/EN (2021-05-01) + ITV – Technical manual NG series (ES), BC0530 pp. 37-39; Wessamat p. 37; NG p. 31
Scotsman – HID312X/HID525X/HID540X Service Manual (June 2025), Controller Diagnostics codes 2 and 3, p. 28
Scotsman – Prodigy Eclipse 600/800/1000 Service Manual (Feb 2008) + Scotsman – EH222 and Condensing Unit Remote Low Side Cuber Service Manual (Apr 2015), Service Diagnosis p. 44–45; Operational characteristics p. 47; Service Diagnosis
Scotsman – Eclipse service manual (eclipse2000); Scotsman – Prodigy EH130 production/service manual (Apr 2008), Eclipse Service Diagnosis p. 41–43; EH130 p. 40–41
Scotsman – BC0530 service manual (March 2020), pp. 37–38
True Manufacturing – True Ice service manual TEC_TM_198 Rev. A (03/2024), pp. 65 and 68
True Manufacturing – True Ice service manual TEC_TM_198 Rev. A (03/2024) + Scotsman – Eclipse 1300/1600 remote low side cuber manual (Sept 2003), True p. 68; Eclipse p. 41
True Manufacturing – True Ice service manual (Spanish) TEC_TM_265 Rev. A, P#857284 (2025-08-27), Solución de problemas, congelación prolongada, p. 64
True Manufacturing – Manuel de service après-vente True Ice, Réf 857284 TEC_TM_266 Rev. A (2024-04-05); Kold-Draft – 60 Series Service Manual rev 04/13/17, True p. 64; Kold-Draft p. 45–48
Hoshizaki – Service manual KM-1100MAJ(50) + Scotsman – Service manual BC0530 (March 2020) + Wessamat – Betriebsanleitung CubeLine DE/EN (2021-05-01), KM p. 11; BC0530 pp. 35, 38; Wessamat pp. 36-37
Scotsman – BC0530 service manual (March 2020), p. 36
ITV – MR 400 Troubleshooting guide + Scotsman – Manual Prodigy Eclipse 1200–2000 (August 2008), MR 400 Long preheating; Prodigy p. 41
ITV – Technical manual IQN/IQF flake and nugget ice machines (ES), pp. 42, 48
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), SL family – Troubleshooting (Anomaly / Cause / Remedy): 'works but ice does not form' and 'no water in the basin'
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), SL family – Troubleshooting (Anomaly / Cause / Remedy): 'does not spray water' and 'pump does not run'
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), SL family – Check out procedure for service (flow chart)
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), SL family – Hydraulic circuit and water inlet valve table
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), SL family – Electric circuit (timer status) and Troubleshooting: 'remains in defrosting', 'sheet of ice under the evaporator'
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), Setting thermostat – evaporator thermostat K22 table and installation advice for R23591
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), Setting thermostat – bin thermostat K50 table; SL Troubleshooting flow chart (room below 7 °C)
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), SL family – Timer table (timer codes per model, voltage and cube)
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), SL family – Troubleshooting (Anomaly / Cause / Remedy): 'not regular or incomplete defrosting'
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), SL family – Troubleshooting (Anomaly / Cause / Remedy): 'ice production decrease', 'water leakages'
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), SL family – Suction values table
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), SL family – Refrigerating circuit (evaporator) and Troubleshooting: 'not regular or incomplete defrosting'
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), SL family – Troubleshooting (Anomaly / Cause / Remedy): 'irregular or opaque ice cube'
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), SLF Line – Electric circuit (control and safety devices); GM360 Line – Electric circuit
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), GM360 Line – Ice machine start up and wiring diagram note
Automatic ice cube maker – Instruktionsbok för rengöring och desinficering (Swedish cleaning and sanitising instructions, file 'COPERTINA svedese 0407'; maker not named, cam-timer spray cuber as sold by ABM AB, probably NTF SL type), Section 2 Cleaning, step 6 note; section 3 Disinfection, step 2 note (undated; copy archived 2026-11-03)
Automatic ice cube maker – Instruktionsbok för rengöring och desinficering (Swedish cleaning and sanitising instructions, file 'COPERTINA svedese 0407'; maker not named, cam-timer spray cuber as sold by ABM AB, probably NTF SL type), Section 2 Cleaning, steps 3, 12, 16–21 (undated; copy archived 2026-11-03)
Automatic ice cube maker – Instruktionsbok för rengöring och desinficering (Swedish cleaning and sanitising instructions, file 'COPERTINA svedese 0407'; maker not named, cam-timer spray cuber as sold by ABM AB, probably NTF SL type), Section 5, 21 kg/day ice cube maker (undated; copy archived 2026-11-03)
Automatic ice cube maker – Instruktionsbok för rengöring och desinficering (Swedish cleaning and sanitising instructions, file 'COPERTINA svedese 0407'; maker not named, cam-timer spray cuber as sold by ABM AB, probably NTF SL type), Section 1 Advice; section 2 Cleaning, steps 4 and 11 (undated; copy archived 2026-11-03)
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), Linear ice makers series – Safety evaporator thermostat (TB models), page 114
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), Linear ice makers series – Rotation sensor, status of rotation sensor, page 112
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), Linear ice makers series – Dirty ice, page 111; auger fixing screw, page 126
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), GM600/1200 Line – Electric circuit (ice machine start-up), page 82; MGT560-900 Line – Electric circuit, page 100
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), SM Line – operating temperature table, page 146
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), Cold flakers series – Safety microswitch, page 149; ice maker doesn't stop, page 154
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), Cold flakers series – Water lack in pump basin, page 154; Poor ice quality, page 155
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), Cold flakers series – Water leakages, page 156
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), Charge control, page 172
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), R404A charges, page 173
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), Electric circuit (relay status), pages 167–168; Micro-switch, page 180; Condenser for the overturning motor, page 178
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), Cubes regulation, pages 176 and 181
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), Water basin level regulation, page 174
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), Pages 182–183
NTF – Technical Documentation, NTF ice makers families (SL, IC, CM, FRM/IW/DSS/ID, SLF/SLT, CVC/CV, GM/MGT, IFT, SM), 2019 (sections dated 2006–2018), Electric circuit (components), page 169; Water-inlet valve, page 171

Ice machine makes little or no ice, or will not harvest

Confirm the fault first

Troubleshoot step by step

Flowchart

Causes, most likely first

Clean a condenser or gas cooler

Check head pressure control

Descale and sanitise an ice machine

Check the ice machine water supply

Check the ice machine water supply

Check a solenoid valve (liquid line or hot gas)

Check ice machine harvest and ice thickness

Descale and sanitise an ice machine

Check a solenoid valve (liquid line or hot gas)

Measure superheat

Measure subcooling

Leak test a refrigeration system

Check ice machine harvest and ice thickness

Descale and sanitise an ice machine

Check a solenoid valve (liquid line or hot gas)

Connect gauges and read pressures

Replace a filter drier

Test whether the compressor pumps

Connect gauges and read pressures

Check a solenoid valve (liquid line or hot gas)

Check ice machine harvest and ice thickness

Descale and sanitise an ice machine

Measure voltage and current under load

Test a contactor

Checks from the manufacturers’ manuals (46)

Service report

Terms in this article

Sources

Confirm the fault first

Troubleshoot step by step

Flowchart

Causes, most likely first

Clean a condenser or gas cooler

Check head pressure control

Descale and sanitise an ice machine

Check the ice machine water supply

Check the ice machine water supply

Check a solenoid valve (liquid line or hot gas)

Check ice machine harvest and ice thickness

Descale and sanitise an ice machine

Check a solenoid valve (liquid line or hot gas)

Measure superheat

Measure subcooling

Leak test a refrigeration system

Check ice machine harvest and ice thickness

Descale and sanitise an ice machine

Check a solenoid valve (liquid line or hot gas)

Connect gauges and read pressures

Replace a filter drier

Test whether the compressor pumps

Connect gauges and read pressures

Check a solenoid valve (liquid line or hot gas)

Check ice machine harvest and ice thickness

Descale and sanitise an ice machine

Measure voltage and current under load

Test a contactor

Checks from the manufacturers’ manuals (46)

Service report

Terms in this article

Sources

Read also