Greenheck DGX Installation, Operation And Maintenance Manual page 13

Troubleshooting – Refrigeration Circuit (optional)
TROUBLESHOOTING NOTE
Before any components are changed on the
refrigeration system, the cause of the failure must be
determined. 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 DDC 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
Compressor will not
run or does not start
Compressor starts
but cuts out on low
pressure.
Low pressure switch
activates at 50 psig
Always have a completed Pre Start-Up Checklist, Unit Start-Up Checklist and Optional Accessories Checklist
prior to requesting parts or service information.
®
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 defective.
High or low pressure switch open or
defective.
Open room thermostat or control (no
cooling required).
Loose wiring.
Low or loss of refrigerant charge.
Airflow restricted.
Restriction in refrigerant line.
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 hrs) 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). If auto
reset (low pressure) does not reset and
everything else is okay, replace switch.
Check room temperature. If temperature is
proper, wait for thermostat to close.
Check all wire terminals and tighten as
necessary.
Check refrigerant pressures.
Check for dirty evaporator coil, dirty filters,
dampers closed, iced evaporator coil,
improper belt, check motor amps, check
duct design.
Check refrigerant pressure, check and
adjust thermal expansion valve. If not
functioning properly, check for pressure
drop across the filter-drier.
Packaged DX Module for Make-Up Air Unit
13