LG AR-DR12-05A Installation And Operation Manual page 58

TROUBLESHOOTING - REFRIGERATION CIRCUIT
Symptom
Insufficient refrigerant charge.
Defective or improperly adjusted
expansion valve.
Low discharge
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.
Compressor short
Poor air distribution.
cycles
High discharge pressure.
Low airflow at evaporator(s).
Incorrect unit selection (oversized).
Refrigerant leak.
Short cycling.
Compressor loses
oil
Refrigerant flood back.
Reheat flush cycle inadequate.
Refrigeration undercharged.
Dirty filter or evaporator coil.
Dirty or clogged condenser coil.
Not enough cooling Air or other non-condensables in
or lack of cooling system.
Restriction in suction and liquid line.
Control contacts stuck.
Excessive load.
Liquid line is frosted
Restriction in liquid line.
or wet
Insufficient evaporator airflow.
Suction line is
frosting Malfunctioning or defective expansion
valve.
Hot gas bypass valve not functioning
properly.
Frost on evaporator
Manual hot gas bypass valve closed.
coil
Low load or airflow.
58
Possible Cause
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.
Check ductwork for recirculating.
See "high discharge pressure".
Check blower operation and airstream restrictions.
Contact factory.
Check system for leaks. Repair leaks and add refrigerant.
Check low pressure control settings.
Check thermal expansion valve setting. Check for refrigerant overcharge. Check
crankcase heater operation.
Contact factory.
Check subcooling. Adjust charge, if necessary.
Check filter, coil and airflow.
Check coil and airflow.
Check equalized high side pressure with equivalent outdoor temperature.
Check for restrictions in refrigerant circuit.
Check wiring.
Add more equipment or reduce room load.
Clear restriction upstream of point of frosting.
Check airflow, check filters, check VFD control signal for proper operation.
Check bulb of thermal expansion valve.
Check valve. If defective, replace.
Open valve.
Increase airflow, check filters.
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Corrective Action