Specifications

Table 43 — Compressor Control Troubleshooting
SYMPTOMS CAUSE REMEDY
COMPRESSOR DOES NOT
RUN
Power line open Check main disconnect.
Control fuse open Check control circuit for ground or short. Replace fuse.
High-Pressure Switch (HPS) tripped Move LOCAL/OFF/REMOTE switch to OFF position
then back to LOCAL or REMOTE position.
Tripped motor overload Check the controls. Find cause of trip. Reset overload.
Loose terminal connection Check connections.
Improperly wired controls Check wiring and rewire.
Low line voltage Check line voltage. Determine location of voltage drop
and remedy deficiency.
Compressor motor defective Check motor winding for open or short. Replace com-
pressor if necessary.
Seized compressor Replace compressor.
Pre-lubrication not successful Check oil pump operation, oil pressure transducer, verify
oil level/flow switch operation.
COMPRESSOR CYCLES
OFF ON LOW PRESSURE
Loss of charge Repair leak and recharge.
Bad transducer Replace transducer.
Low refrigerant charge Add refrigerant.
Failed expansion device Repair/replace as needed.
COMPRESSOR SHUTS
DOWN ON HIGH PRES-
SURE CONTROL
High-pressure switch erratic in action Replace switch.
Compressor discharge valve partially closed Open valve or replace if defective.
Condenser fan(s) not operating (air cooled units) Check wiring. Repair or replace motor(s) if defective.
Condenser coil plugged or dirty (air cooled units) Clean coil.
Condenser water valve not operating (water
cooled units)
Check wiring. Repair or replace valve if defective
Circuit overcharged Clean condenser.
Liquid valve closed* Open valve or replace if defective.
UNIT OPERATES LONG OR
CONTINUOUSLY
Low refrigerant charge Add refrigerant.
Control contacts fused Replace control.
Partially plugged or plugged expansion valve or
filter drier
Clean or replace.
Defective insulation Replace or repair.
Service load exceeding design capacity Keep doors and windows closed.
Inefficient compressor Check loader solenoid valves. Replace if necessary.
SYSTEM NOISES Piping vibration Support piping as required.
Expansion valve hissing Add refrigerant.
Check for plugged liquid line filter drier.
Compressor noisy Replace compressor (worn bearings).
Check for loose compressor bolts securing compressor
to cooler.
COMPRESSOR LOSES OIL Leak in system Find and repair leak.
Mechanical damage to rotors Replace compressor.
HOT LIQUID LINE Shortage of refrigerant due to leak Repair leak and recharge.
FROSTED LIQUID LINE Shutoff valve partially closed or restricted Open valve or remove restriction.
COMPRESSOR LOADERS
NOT WORKING PROPERLY
Burned out coil Replace coil.
Defective capacity control valve Replace valve.
Miswired solenoid Rewire correctly.
*30GX251, 265 sizes have two Circuit A discharge and liquid valves.
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
CPM-B1CPM-A1HSIO-IIPSIO-2-J8DSIO-EXV-J2
DSIO-HV-J2
PSIO-1-J8
Fig. 24 — Sensor Bus Wiring (Communications)
65