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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 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
Airflow restricted.
out on low
pressure
Low pressure
switch
Restriction in refrigerant line.
activates at
50 PSIG
Defective low pressure switch.
Always have a completed Pre-Start-Up Checklist and Start-Up Checklist prior to requesting parts or service
information.
36
VersiVent Energy Recovery Ventilator
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 (two
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
600 psi and will not reset above 420 psi for R-410A). Replace if
defective.
Switch will open at 50 psi and auto-close at 90 psi. Replace if
defective.
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.
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