Superheat hunting (the valve hunts)

Causes, most likely first

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

1. 1
   Flowchart A

   The bulb has poor contact with the suction line and reacts too late.

   Remedy: Mount the bulb on a straight, clean pipe in the clock position the manufacturer specifies, tighten the clamp and insulate.

   🛠 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.

   Mount the bulb and equaliser line

   The TXV regulates on what its bulb feels. A bulb in the wrong place, with poor contact or without insulation gives hunting or wrong superheat, and an equaliser connected before the bulb disturbs the control.

   1. Choose the position. Choose a horizontal part of the suction line just after the evaporator, before any trap or riser, and not close to a heat source or where liquid may collect.

      ✓ Check: The chosen section is horizontal, close to the evaporator outlet and free of traps.

   2. Clean the pipe. Clean the pipe at the bulb position down to bare metal with a cleaning cloth or fine abrasive. Remove frost and paint. The pipe can be cold; wear gloves.

      ✓ Check: The pipe surface is bright and clean where the bulb will sit.

   3. Fit the bulb at the right clock position. Clamp the bulb along the pipe with the metal clamp supplied with the valve. On smaller suction lines place it on top, on larger lines at about 4 or 8 o'clock, never at the bottom where oil runs. Follow the valve manufacturer's instructions for your pipe size.

      ✓ Check: The bulb lies flat along the pipe at the right position and cannot be turned by hand.

   4. Insulate the bulb. Wrap the bulb and the pipe with closed-cell insulation tape so that ambient air and radiant heat cannot affect it.

      ✓ Check: The bulb and the clamp are fully covered and the insulation is sealed at the ends.

   5. Connect the equaliser after the bulb. Connect the external equaliser line on the top of the suction line, a short distance after the bulb (in the flow direction). If it must be brazed, the circuit is opened: recover the refrigerant (F-gas certification), braze with nitrogen flowing and observe hot work rules, then pressure test with nitrogen and evacuate.

      ✓ Check: The equaliser is connected downstream of the bulb and the joint is tight in the pressure test.

   6. Check the superheat. Start the system, let it run stable and measure the superheat.

      ✓ Check: The superheat is stable without hunting and at the value given for the system.

2. 2
   Flowchart B

   The superheat is set too low, so the valve swings against the liquid limit.

   Remedy: Raise the setting in steps and wait for it to settle between each step.

   🛠 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.

   Adjust superheat and size the expansion valve

   A thermostatic expansion valve (TXV) is adjusted only after other causes are ruled out. Small steps and patience give stable superheat without liquid reaching the compressor.

   1. Rule out other causes first. Check charge, sight glass, liquid line restriction, bulb mounting and equaliser line (see those guides). Do not use the adjustment screw to hide another fault.

      ✓ Check: Other causes are ruled out or fixed.

   2. Measure superheat. In stable operation, measure suction pressure at the evaporator outlet and the pipe temperature at the bulb. Superheat = pipe temperature − saturation temperature (dew point for blends). Find the target in the evaporator or valve maker's data.

      ✓ Check: You have a steady superheat value and a target to compare with.

   3. Adjust in small steps. Remove the cap and turn the spindle a quarter to half a turn. On most valves clockwise increases superheat; check the maker's marking. Note how many turns you have made.

      ✓ Check: The spindle is turned a known amount in the right direction.

   4. Wait for stable operation. Wait at least 15 minutes before you measure again; the valve and evaporator react slowly.

      ✓ Check: Superheat stays steady over several readings.

   5. Repeat and protect the compressor. Repeat until the target is reached. Check suction superheat at the compressor as well and look for frost on the compressor; never set superheat so low that liquid reaches the compressor.

      ✓ Check: Evaporator superheat is at the target and there is no sign of liquid at the compressor.

   6. Judge the valve size. Hunting with large swings that will not settle can mean the valve or orifice is too large; high superheat with the valve fully open can mean it is too small. Compare the valve capacity at the actual evaporating temperature, liquid temperature and pressure drop with the evaporator load in the maker's selection data. Changing the orifice opens the circuit and needs F-gas certified personnel.

      ✓ Check: Valve capacity matches the load, or you have a documented reason to change it.

   7. Refit the cap and record. Refit the cap with its seal, leak test it and write down the final setting and superheat.

      ✓ Check: The cap is tight and the setting is recorded.

   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.

3. 3
   Flowchart C

   Flash gas ahead of the valve gives an uneven flow through the valve.

   Remedy: Troubleshoot the bubbles in the sight glass: refrigerant charge, filter drier and pressure drop in the liquid line.

   🛠 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.

   Read the sight glass and moisture indicator

   The sight glass shows whether the liquid line is full of liquid, and the moisture indicator whether the refrigerant is dry. Both must be read in stable operation and together with other measurements.

   1. Check marking and position. Check that the sight glass is marked for the refrigerant in the system and its pressure, and that it sits in the liquid line after the filter drier.

      ✓ Check: Marking and position are correct; otherwise the colour reading cannot be trusted.

   2. Run until stable. Let the system run at steady load for at least 15 minutes, not just after start, a defrost or a capacity step. Wipe the glass and light it with a torch.

      ✓ Check: Pressures and temperatures are steady and you can see clearly into the glass.

   3. Read the moisture indicator. Compare the indicator colour with the colour scale printed on the sight glass ring. Colours differ between makers (often green for dry and yellow for wet). The indicator reacts slowly: after a drier change it can take many hours to show the true value.

      ✓ Check: The colour matches the 'dry' field on the scale; a 'wet' colour means moisture in the system.

   4. Read the liquid. Look for a full, clear liquid column, foam or streams of bubbles. Note that a completely clear glass can also mean it is full of vapour in a nearly empty system; confirm with subcooling.

      ✓ Check: You can say whether the glass is full of liquid, and subcooling confirms it.

   5. Judge the bubbles. Bubbles are normal at start, after defrost, during capacity changes and when the liquid flashes because of pressure drop, a vertical lift or warm surroundings. Persistent bubbles in stable operation call for a subcooling measurement and a check for restriction before you suspect undercharge.

      ✓ Check: You know whether the bubbles come from the operating state, a restriction or too little refrigerant.

   6. Act on the result. Moisture: find the cause (leak, poor evacuation), replace the filter drier and evacuate. Too little refrigerant: never add refrigerant to clear bubbles; leak test, repair, recover and weigh in the correct charge. Work that opens the circuit needs F-gas certified personnel.

      ✓ Check: After the action the glass is full of liquid in stable operation and the indicator returns to 'dry'.

   Find a restriction in the liquid line

   A partly blocked filter drier, strainer or valve makes the liquid flash and starves the evaporator. Pressure drop shows up as a temperature drop at the restriction.

   1. Confirm the symptoms. In stable operation, measure superheat and subcooling. A restriction typically gives high superheat and low suction pressure while subcooling before the restriction is normal or high.

      ✓ Check: The measurements fit a restriction rather than a simple shortage of refrigerant.

   2. Look and feel along the line. Follow the liquid line from the condenser or receiver. Look for sweating or frost and feel for a cold spot right after a component. Wear gloves against cold burns.

      ✓ Check: You have found any spot that is clearly colder than the line before it.

   3. Measure across each component. Clamp thermometers before and after the filter drier, solenoid valve, strainer, sight glass and shut-off valves, one component at a time.

      ✓ Check: The temperature is the same on both sides of a free component; a noticeable drop of more than a degree or two marks the restriction.

   4. Measure the pressure drop. Where there are service ports before and after the filter drier or valve, measure the pressure on both sides and compare with the maker's permitted pressure drop.

      ✓ Check: The pressure drop is within the maker's data, or the component is confirmed as restricted.

   5. Check the sight glass and valves. Bubbles after a component but clear liquid before it point to that component. Check that hand and shut-off valves are fully open and that the solenoid valve opens fully when energised.

      ✓ Check: All valves are fully open and you know where flashing starts.

   6. Repair. Replacement opens the circuit and needs F-gas certified personnel: pump down or recover, never trap liquid between closed valves (especially CO2), braze with nitrogen flowing, pressure test, evacuate and recharge by weight.

      ✓ Check: After repair there is no temperature drop across the component and superheat is back to normal.

   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.

   Continue with: Bubbles in the sight glass →

4. 4
   Flowchart D

   The valve is too large for the load.

   Remedy: Fit a smaller orifice or valve. With a varying load, an electronic valve is a better choice.

   🛠 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.

   Adjust superheat and size the expansion valve

   A thermostatic expansion valve (TXV) is adjusted only after other causes are ruled out. Small steps and patience give stable superheat without liquid reaching the compressor.

   1. Rule out other causes first. Check charge, sight glass, liquid line restriction, bulb mounting and equaliser line (see those guides). Do not use the adjustment screw to hide another fault.

      ✓ Check: Other causes are ruled out or fixed.

   2. Measure superheat. In stable operation, measure suction pressure at the evaporator outlet and the pipe temperature at the bulb. Superheat = pipe temperature − saturation temperature (dew point for blends). Find the target in the evaporator or valve maker's data.

      ✓ Check: You have a steady superheat value and a target to compare with.

   3. Adjust in small steps. Remove the cap and turn the spindle a quarter to half a turn. On most valves clockwise increases superheat; check the maker's marking. Note how many turns you have made.

      ✓ Check: The spindle is turned a known amount in the right direction.

   4. Wait for stable operation. Wait at least 15 minutes before you measure again; the valve and evaporator react slowly.

      ✓ Check: Superheat stays steady over several readings.

   5. Repeat and protect the compressor. Repeat until the target is reached. Check suction superheat at the compressor as well and look for frost on the compressor; never set superheat so low that liquid reaches the compressor.

      ✓ Check: Evaporator superheat is at the target and there is no sign of liquid at the compressor.

   6. Judge the valve size. Hunting with large swings that will not settle can mean the valve or orifice is too large; high superheat with the valve fully open can mean it is too small. Compare the valve capacity at the actual evaporating temperature, liquid temperature and pressure drop with the evaporator load in the maker's selection data. Changing the orifice opens the circuit and needs F-gas certified personnel.

      ✓ Check: Valve capacity matches the load, or you have a documented reason to change it.

   7. Refit the cap and record. Refit the cap with its seal, leak test it and write down the final setting and superheat.

      ✓ Check: The cap is tight and the setting is recorded.

5. 5

   Thermostatic valve: the external equaliser line is missing, blocked, kinked or connected in the wrong place, or a valve with internal equalisation is used on an evaporator with a large pressure drop (distributor).

   Remedy: Check that the equaliser line is open and connected to the suction line just after the bulb, downstream of it. Fit a valve with external equalisation if the evaporator has a distributor.

   🛠 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.

   Mount the bulb and equaliser line

   The TXV regulates on what its bulb feels. A bulb in the wrong place, with poor contact or without insulation gives hunting or wrong superheat, and an equaliser connected before the bulb disturbs the control.

   1. Choose the position. Choose a horizontal part of the suction line just after the evaporator, before any trap or riser, and not close to a heat source or where liquid may collect.

      ✓ Check: The chosen section is horizontal, close to the evaporator outlet and free of traps.

   2. Clean the pipe. Clean the pipe at the bulb position down to bare metal with a cleaning cloth or fine abrasive. Remove frost and paint. The pipe can be cold; wear gloves.

      ✓ Check: The pipe surface is bright and clean where the bulb will sit.

   3. Fit the bulb at the right clock position. Clamp the bulb along the pipe with the metal clamp supplied with the valve. On smaller suction lines place it on top, on larger lines at about 4 or 8 o'clock, never at the bottom where oil runs. Follow the valve manufacturer's instructions for your pipe size.

      ✓ Check: The bulb lies flat along the pipe at the right position and cannot be turned by hand.

   4. Insulate the bulb. Wrap the bulb and the pipe with closed-cell insulation tape so that ambient air and radiant heat cannot affect it.

      ✓ Check: The bulb and the clamp are fully covered and the insulation is sealed at the ends.

   5. Connect the equaliser after the bulb. Connect the external equaliser line on the top of the suction line, a short distance after the bulb (in the flow direction). If it must be brazed, the circuit is opened: recover the refrigerant (F-gas certification), braze with nitrogen flowing and observe hot work rules, then pressure test with nitrogen and evacuate.

      ✓ Check: The equaliser is connected downstream of the bulb and the joint is tight in the pressure test.

   6. Check the superheat. Start the system, let it run stable and measure the superheat.

      ✓ Check: The superheat is stable without hunting and at the value given for the system.

6. 6
   Flowchart E

   Electronic controller: wrong parameters, a faulty pressure sensor, or a swinging condensing pressure that disturbs the valve.

   Remedy: Check pressure and temperature sensors against calibrated instruments and the controller settings. Stabilise the condensing pressure.

   🛠 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 a sensor against a reference

   A temperature or pressure sensor that reads wrong makes the controller regulate wrong: wrong superheat, wrong defrost, false alarms. Compare it with a calibrated reference before changing settings or parts.

   1. Fit the reference next to the sensor. Fasten a calibrated thermometer probe beside the temperature sensor on the same pipe or in the same air stream, with heat-conducting paste and insulation. For a pressure sensor, connect a calibrated gauge to a service port at the same point in the circuit. Wear goggles and gloves when connecting to the refrigerant circuit.

      ✓ Check: The reference reading is steady for a few minutes.

   2. Compare with the controller reading. Read the live value of the sensor in the controller display or service tool at the same time as the reference.

      ✓ Check: The difference is within the tolerance given by the sensor or controller manufacturer (for a temperature sensor typically within about 1 K).

   3. Check offsets and sensor type. In the controller parameter list, check that the sensor type (e.g. NTC, PT1000, 0–10 V, 4–20 mA), the pressure range and any calibration offset match the fitted sensor. Record the original values before changing anything.

      ✓ Check: Sensor type, range and offset in the controller match the sensor data sheet.

   4. Measure the sensor resistance. Isolate and lock off the controller, disconnect the sensor and measure its resistance with a multimeter while the reference shows the temperature at the sensor. Compare with the manufacturer's resistance table. A PT1000 reads 1000 Ω at 0 °C; an ice-water bath gives a simple 0 °C check point.

      ✓ Check: The resistance matches the table value for the reference temperature; OL or 0 Ω means a broken or shorted sensor or cable.

   5. Check the sensor location and mounting. Inspect the pipe clamp or pocket: firm metal-to-metal contact, heat-conducting paste, insulation against the surrounding air and the correct position (e.g. evaporator outlet, not in the air stream of a fan).

      ✓ Check: The sensor sits firmly at the correct point and is insulated.

   6. Reconnect and confirm. Reconnect the sensor, restore power and compare the reading with the reference once more. Replace a sensor that is out of tolerance with one of the same type.

      ✓ Check: Controller and reference agree within the tolerance.

   Check an electronic expansion valve

   An electronic expansion valve (EEV) is only as good as its sensors, cable and driver. Check them in that order before you blame the valve itself.

   1. Read driver alarms and valve opening. Read the alarm log, the superheat setpoint, the measured superheat and the valve opening (%) on the driver or service tool. Note whether the valve is stuck at 0 % or 100 % or hunting.

      ✓ Check: You know what the driver measures and what it is trying to do with the valve.

   2. Check the sensors. Compare the suction pressure transducer with a calibrated gauge at the same point, and the suction temperature sensor with a reference thermometer next to it. Check that the sensor is clamped tight on clean pipe and insulated.

      ✓ Check: Both readings agree with the references within the sensor's tolerance; otherwise fix the sensor first.

   3. Isolate and measure the coil. Isolate the driver supply, lock off and prove dead. Disconnect the valve plug and measure the resistance of each winding (for a typical bipolar stepper, two windings), and from each winding to the valve body.

      ✓ Check: The windings read the same as each other and match the valve data sheet; there is no connection to the body. OL means an open winding.

   4. Check cable and connector. Check the cable for damage and the connector for moisture, corrosion and loose pins. Check that cable length and shielding follow the valve maker's limits.

      ✓ Check: The cable is intact, the connector dry and tight, and the cable within the specified length.

   5. Drive the valve manually. Reconnect and switch on. With the service tool, set the valve to manual and move it in steps from closed towards open while you watch suction pressure and superheat. Do not leave it open so far that liquid reaches the compressor. On CO2 systems do not trap liquid between a closed EEV and another closed valve.

      ✓ Check: Suction pressure and superheat change with each step; no response means a stuck valve or a dead driver output.

   6. Return to reference and automatic. Let the driver initialise the valve to its reference (closed) position and return it to automatic. If the driver has a back-up module that closes the valve on power failure, check its status.

      ✓ Check: The valve homes without alarms and superheat settles at the setpoint in automatic.

   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.

7. 7

   A loose cable or poor shielding to the pressure or temperature sensor (electronic valve).

   Remedy: Check connectors, cables and shielding, and that the sensor cables are not run next to power cables.

   🛠 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 an electronic expansion valve

   An electronic expansion valve (EEV) is only as good as its sensors, cable and driver. Check them in that order before you blame the valve itself.

   1. Read driver alarms and valve opening. Read the alarm log, the superheat setpoint, the measured superheat and the valve opening (%) on the driver or service tool. Note whether the valve is stuck at 0 % or 100 % or hunting.

      ✓ Check: You know what the driver measures and what it is trying to do with the valve.

   2. Check the sensors. Compare the suction pressure transducer with a calibrated gauge at the same point, and the suction temperature sensor with a reference thermometer next to it. Check that the sensor is clamped tight on clean pipe and insulated.

      ✓ Check: Both readings agree with the references within the sensor's tolerance; otherwise fix the sensor first.

   3. Isolate and measure the coil. Isolate the driver supply, lock off and prove dead. Disconnect the valve plug and measure the resistance of each winding (for a typical bipolar stepper, two windings), and from each winding to the valve body.

      ✓ Check: The windings read the same as each other and match the valve data sheet; there is no connection to the body. OL means an open winding.

   4. Check cable and connector. Check the cable for damage and the connector for moisture, corrosion and loose pins. Check that cable length and shielding follow the valve maker's limits.

      ✓ Check: The cable is intact, the connector dry and tight, and the cable within the specified length.

   5. Drive the valve manually. Reconnect and switch on. With the service tool, set the valve to manual and move it in steps from closed towards open while you watch suction pressure and superheat. Do not leave it open so far that liquid reaches the compressor. On CO2 systems do not trap liquid between a closed EEV and another closed valve.

      ✓ Check: Suction pressure and superheat change with each step; no response means a stuck valve or a dead driver output.

   6. Return to reference and automatic. Let the driver initialise the valve to its reference (closed) position and return it to automatic. If the driver has a back-up module that closes the valve on power failure, check its status.

      ✓ Check: The valve homes without alarms and superheat settles at the setpoint in automatic.