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Troubleshooting – Refrigeration Circuit
Symptom
Possible Cause
Excessive load on evaporator coil.
Compressor is unloaded.
(digital scroll)
Expansion valve sensing bulb not secured to
High suction
suction line.
pressure
Thermostatic expansion valve. Overfeeding.
Room load too large.
Overcharged.
Thermal expansion valve setting.
Air inlet to condenser dirty or obstructed.
Condenser fan motor defective.
High discharge
Too much refrigerant.
pressure
Non-condensable in system.
Dirty condenser coil.
Condenser fan not running or running
backwards.
High load conditions.
Refrigerant undercharge/loss of refrigerant
charge.
Blower running backward.
Low entering air temperature.
(Low load conditions).
Refrigerant leak.
Low suction
pressure
Evaporator dirty or iced-up, or airflow
restricted.
Plugged liquid line filter-drier.
Improper hot gas bypass setting.
Expansion valve defective, superheat too
high or valve too small.
Moisture in system, check sight glass.
Insufficient refrigerant charge.
Defective or improperly adjusted expansion
Low discharge
valve.
pressure
Low suction pressure.
Faulty condenser temperature controls.
(Condensing fan cycle switch).
38
VersiVent Energy Recovery Ventilator
Corrective Action
Check for high entering wet bulb temperature, check for
excessive air flow.
Check digital scroll controller signal and solenoid valve.
Check the thermal expansion valve, ensure bulb is insulated.
Check superheat. If superheat is high, then valve is choking
refrigerant flow.
• Check bulb for contact.
• Adjust valve for superheat ~10°F.
• Replace valve power head or valve.
Check bulb location and clamping. Adjust superheat. Replace
expansion valve power head.
Reduce the load or add more equipment.
Check pressures and subcooling.
Check thermal expansion setting and calibrate
superheat / subcooling.
Check for proper clearances and possible air recirculating.
Clean coil.
Check condenser fan motor.
Check subcooling. Remove excess refrigerant.
Remove non-condensable from system.
Clean condenser coil.
Check electrical circuit and fuse. Check fan cycling controls.
Add more equipment or reduce load.
Check pressures and subcooling.
Confirm blower rotation. If reversed, interchange any two wires
from 3-phase disconnect.
Check entering air wet bulb conditions.
Check system for leaks. Repair leaks and add refrigerant.
Clean the coil. Check fan operation. Check airflow.
Replace filter-drier, check psi across filter.
Check setting and correct as required.
Adjust valve for proper superheat or replace the expansion
valve if too small or defective.
Reclaim refrigerant, check for leaks, recharge.
Check subcooling, check for leak. Repair leak and add
refrigerant.
Check superheating and adjust thermal expansion valve.
See "low suction pressure".
Check condenser controls and reset to obtain desired
condensing temperature.
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