Greenheck ERCH - Energy Recovery Unit with Packaged DX (468151) - Manual (Page 48)

48
Energy Recovery Unit with Packaged DX
Troubleshooting - General Refrigeration Circuit
Symptom Possible Cause Corrective Action
Low suction
pressure
Refrigerant undercharge . Check pressures and subcooling .
Blower running backward .
Interchange any two wires from 3 phase
disconnect .
Loose blower, pulley or belts . Check drive pulley alignment, belt tension .
Low entering air temperature (low load
condition) .
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 .
Check defrost system . Clean the coil .
Check fan operation . Check airflow .
Plugged liquid line filter-drier . Replace filter-drier .
Improper suction pressure regulator 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 . 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 .
Check condenser controls and reset to obtain
desired condensing temperature .
Compressor
short cycles
Thermostat location or malfunction .
Check thermostat, check heat anticipator
setting .
Improper refrigerant charge . Check subcooling, verify superheat .
Defective high or low pressure control . Check high or low pressure switch .
Liquid floodback . Possible tight bearings, see above .
Defective expansion valve . Check thermal expansion valve and superheat .
Poor air distribution . Check ductwork for recirculating .
High discharge pressure . See “High discharge pressure” .
Leaking discharge valves in compressor . See “High suction pressure” .
Low airflow at evaporator(s) .
Check blower operation and airstream
restrictions .
Incorrect unit selection (oversized) . Contact factory .
Always have a completed Pre-Start-Up Checklist, unit Start-Up Checklist, and Optional Accessories Checklist prior to requesting parts or
service information.