LG GEN2 Series Installation And Operation Manual page 54

Troubleshooting – Refrigeration Circuit
TROUBLESHOOTING NOTE
Before any components are changed on the
refrigeration system, the cause of the failure must be
identified. Further problems will exist unless the true
cause or problem is identified and corrected.
NOTE: Unit is equipped with a phase loss/phase reversal control. If system does not start, check phase of electrical
supply.
The first step in troubleshooting a refrigeration circuit is to examine the microprocessor controller and digital scroll compressor
controller (if present) and see if there is a fault code. The next step is to check airflow conditions
(e.g. improper ductwork, atypical wet bulb / dry bulb, etc.). After these steps have been eliminated, proceed with
troubleshooting by following this guide.
Symptom Possible Cause
Open disconnect switch or circuit
breaker.
Compressor contactor not closing.
Blown fuse or tripped breaker.
Low line voltage.
Compressor motor protector open.
Compressor
will not run
or does not
start
Compressor defective.
High pressure switch open
or defective.
Low pressure switch open
or defective.
Open room thermostat or control.
(No cooling required).
Loose wiring.
Low or loss of refrigerant charge.
Compressor
starts but
cuts out on
Airflow restricted.
low pressure
Low pressure
switch
Restriction in refrigerant line.
activates at
50 PSIG
(PDX) or 25
Defective low pressure switch.
PSIG (ASHP)
Always have a completed Pre-Start-Up Checklist and Start-Up Checklist prior to requesting parts or service information.
IMPORTANT
Do not release refrigerant to the atmosphere! If
required service procedures include the adding or
removing of refrigerant, the service technician must
comply with all federal, state and local laws. The
procedures discussed in this manual should only be
performed by a qualified EPA Certified Technician.
Corrective Action
Close switch and/or breaker.
Check voltage to contactor coil, transformer, slave relay,
system. Replace parts as necessary.
Check for reason and repair. Replace fuse after correcting
problem.
Check line voltage. If more than 10% from compressor
marking, correcting is necessary.
Motor thermal protector automatically resets. Allow time
(2 hours) for compressor to cool down so protector will
reset. Restart and check for reason overheat occurred.
Check motor for open circuit, short circuit, grounded
windings, or burn out. Compressor may be seized; check
refrigerant. If necessary, replace compressor.
If manual reset (high pressure), reset switch. (Switch
opens at 610 psi and will not reset above 420 psi for
R-410A). Replace if defective.
See switch label for set point.
Check room temperature. If temperature is proper, wait
for thermostat to close.
Check all wire terminals and tighten as necessary.
Check refrigerant pressures and temperatures
(subcooling.)
Check for dirty evaporator coil, dirty filters, dampers
closed, iced evaporator coil, improper belt, check motor
amps, check duct design.
Check refrigerant pressures, look for frosted tubing and
components indicating a restriction. Check pressure drop
across the filter drier.
Replace.