Greenheck Fan Energy Recovery Ventilator with Heat Pump 473501 - Manual (Page 35)

35 Model ERCH-HP Energy Recovery Unit
Troubleshooting – Refrigeration Circuit
Symptom Possible Cause Corrective Action
Low or no
oil pressure
Low oil level (trapped oil in evaporator or suction
line).
Thoroughly defrost evaporator. After defrost,
observe level, add oil. Check for leaks. Check lines
for proper slope and traps.
Excessive liquid refrigerant in the crankcase.
Adjust expansion valve for higher superheat. Check
crankcase heater.
Worn oil pump. Replace the oil pump.
Worn compressor bearings. Replace the compressor.
Loose fitting on oil line or pump housing gasket
leaking. Check and tighten system. Check bottom plate or
compressor.
Compressor short cycling. Check low pressure control setting.
Compressor
loses oil
Refrigerant leak.
Check system for leaks. Repair leaks and add
refrigerant.
Short cycling. Check low pressure control settings.
Refrigerant flood back.
Check thermal expansion valve setting. Check for
refrigerant overcharge.
Improper piping or traps. Verify proper piping slopes.
Reheat flush cycle inadequate. Contact factory.
Running cycle is
too long or unit
operates
continuously
Refrigeration undercharged. Check subcooling.
Dirty filter or evaporator coil. Check filter, coil and airflow.
Dirty or clogged condenser coil. Check coil and airflow.
Air or other non-condensables in system.
Check equalized high side pressure with equivalent
outdoor temperature.
Defective compressor. See “High suction pressure”.
Restriction in suction and liquid line. Check for restrictions in refrigerant circuit.
Control contacts stuck. Check wiring.
Excessive load. Add more equipment or reduce room load.
Too low of a system thermostat setting or
defective thermostat.
Adjust or replace thermostat.
Liquid line
is too hot
Refrigerant undercharge. Adjust the charge by subcooling.
High discharge pressure. See “High discharge pressure”.
Liquid line is
frosted or wet
Restriction in liquid line. Clear restriction upstream of point of frosting.
Suction line
is frosting
Insufficient evaporator airflow.
Check airflow, check filters, check drive for loose
parts or belts.
Restriction in suction or liquid line. Restriction upstream of point of frosting.
Malfunctioning or defective expansion valve. Check bulb of thermal expansion valve.
Frost on
evaporator coil
Hot gas bypass valve not functioning properly. Check valve. If defective, replace.
Manual hot gas bypass valve closed. Open valve.
Always have a completed Pre Start-Up Checklist and Unit Start-Up Checklist prior to requesting parts or service information.