Greenheck DGX Installation, Operation And Maintenance Manual page 16

Symptom Possible Cause
Insufficient refrigerant charge.
Defective or improperly adjusted
Low discharge
expansion valve.
pressure
Low suction pressure.
Faulty condenser temperature controls.
(Condensing fan cycle switch).
Thermostat location or controls
malfunction.
Improper refrigerant charge.
Defective high or low pressure control.
Liquid floodback.
Defective expansion valve.
Compressor short
cycles
Poor air distribution.
High discharge pressure.
Leaking discharge valves in compressor.
Low airflow at evaporator(s).
Incorrect unit selection (oversized).
Always have a completed Pre Start-Up Checklist, Unit Start-Up Checklist and Optional Accessories Checklist
prior to requesting parts or service information.
16
Packaged DX Module for Make-Up Air Unit
Corrective Action
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.
Check thermostat, check heat anticipator
setting.
Check subcooling, verify superheat.
Check high or low pressure switch.
Possible tight bearings, see above.
Check thermal expansion valve and
superheat.
Check ductwork for recirculating.
See "high discharge pressure".
See "high suction pressure".
Check blower operation and airstream
restrictions.
Contact factory.
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