Trouble Shooting and Service Chart
COMPLAINT
POSSIBLE CAUSE
REPAIR
Compressor will
1. Line disconnect switch open.
1. Close start or disconnect switch.
A
not start - no
2. Fuse removed or blown.
2. Replace fuse.
hum
3. Overloaded protector tripped.
3. Refer to electrical section.
4. Control stuck in open position.
4. Repair or replace control.
5. Control off due to cold location.
5. Relocate control.
6. Wiring improper or loose.
6. Check wiring against diagram.
Compressor will
1. Improperly wired.
1. Check wiring against diagram.
B
not start - hums
2. Low voltage to unit.
2. Determine reason and correct.
but trips on
3. Starting capacitor defective.
3. Determine reason and replace.
overload
4. Relay failing to close.
4. Determine reason and correct, replace
protector
if necessary.
5. Compressor motor has a winding open
5. Replace compressor.
or shorted.
6. Internal mechanical trouble in
6. Replace compressor.
compressor.
7. Liquid refrigerant in compressor.
7. Add crankcase heater and/or accumulator.
Compressor
1. Improperly wired.
1. Check wiring against diagram.
C
starts, but does
2. Low voltage to unit.
2. Determine reason and correct.
not switch off
3. Relay failing to open.
3. Determine reason and correct, replace
of start winding
if necessary.
4. Run capacitor defective.
4. Determine reason and replace.
5. Excessively high discharge pressure.
5. Check discharge shut-off valve, possible
overcharge, or insufficient cooling on
condenser.
6. Compressor motor has winding open
6. Replace compressor.
or shorted.
7. Internal mechanical trouble in
7. Replace compressor.
compressor (tight).
Compressor
1. Additional current passing through
1. Check wiring diagram. Check for
D
starts and runs,
overload protector.
added fan motors, pumps, etc., con-
but short cycles
nected to wrong side of protector.
on overload
2. Low voltage to unit ( or unbalanced if
2. Determine reason and correct.
protector
three phase).
3. Overload protector defective.
3. Check current, replace protector.
4. Run capacitor defective.
4. Determine reason and replace.
5. Excessive discharge pressure.
5. Check ventilation, restrictions in cool-
ing medium, restrictions in refrigera-
tion system.
6. Suction pressure too high.
6. check for possibility of misapplication.
Use stronger unit.
7. Compressor too hot - return gas hot.
7. Check refrigerant charge (fix leak), add
if necessary.
8. Compressor motor has a winding
8. replace compressor.
shorted.
Unit runs OK,
1. Overload protector.
1. See D. above.
E
but short
2. Thermostat.
2. Differential set too close - widen.
cycles on
3. High pressure cut - out due to:
a. Insufficient air or water supply.
3a.
Check air or water supply to con-
denser - correct.
b. Overcharge.
3b.
Reduce refrigerant charge.
c. Air in system.
3c.
Purge.
4. Low pressure cut - out due to:
a. Liquid line solenoid leaking.
4a.
Replace.
b. Compressor valve leak.
4b.
Replace.
c. Undercharge.
4c.
Fix leak, add refrigerant.
d. Restriction in expansion device.
4d.
Replace device.
