LG GEN2 Series Installation And Operation Manual page 55

Troubleshooting – Refrigeration Circuit
Symptom Possible Cause
Refrigerant overcharge.
Compressor
Condenser fan motor defective.
starts but
Condenser coil inlet obstructed or dirty.
cuts out
on high
Air or non-condensables in system.
pressure
switch
Defective high pressure switch.
High pressure
activates at
Restriction in discharge or liquid line.
600 PSIG
Condensing fan relay not pulling in.
Low voltage.
Sustained high discharge pressure.
High suction and discharge pressures.
Compressor
cuts out Defective compressor overload.
on thermal
overload Improper refrigerant charge.
Improperly wired.
Loose wiring.
Defective start relay.
Motor windings damaged.
Improperly wired.
Low line voltage.
Loose wiring.
Compressor
hums, but
Defective start relay.
will not start
Motor winding damaged.
Internal compressor mechanical
damage.
Refrigerant overcharge.
Liquid floodback.
Tubing rattle.
Compressor
noisy or
Scroll compressor rotating in reverse.
vibrating
(3-phase)
Damaged compressor.
Improper mounting on unit base.
Always have a completed Pre-Start-Up Checklist and Start-Up Checklist prior to requesting parts or service information.
Corrective Action
Check pressures, charge by subcooling.
Check fan motor.
Check coil and clearances. Clean coil if necessary.
Check high side equalized pressures, check thermal
expansion valves.
Replace.
Check refrigerant line pressures, check thermal
expansion valves, replace any defective component.
Replace.
Check voltage.
Check running amperage and conditions described under
"low suction pressure" symptoms.
Check thermal expansion valve setting, check for air in
system. Check air conditions and cfm.
If compressor is hot, allow compressor to cool for two
hours. Recheck for open circuit.
Check subcooling.
Review wiring schematics.
Check all connections.
Replace relay.
Verify amp draw.
Review wiring schematics.
Check voltage.
Check all connections.
Replace relay.
Verify amp draws. Replace compressor if necessary.
Replace.
Check pressures and subcooling.
Check thermal expansion valve setting. Check for
refrigerant overcharge.
Dampen tubing vibration by taping or clamping. Carefully
bend tubing away from contact where possible.
Check high and low side pressures during operation to
confirm. Rewire for opposite rotation.
Replace the compressor.
Check that compressor is properly isolated and mounting
bolts are tight.