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