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Symptom
A. Compressor neither starts nor hums
Probable Cause
1. No power to unit.
2. No call for cooling.
control wiring.
3. Anti-short cycle
timer has not
times out.
4. Unit locked out by
reset relay.
5. Compressor contactor
will not close.
6. Compressor winding
stat open.
CSRA-SVX01A-EN
Troubleshooting
Recommended Action
Check for the following:
a. Disconnect switch open.
b. Fuse(s) blown.
Check for the following:
a. Defective thermostat.
b. Broken or improper
c. Blown control power fuse.
Wait at least 3 minutes
for the anti-short cycle
timer to time out.
Check for the following:
a. Excessive discharge
pressure; see "Discharge
Pressure Too High"
b. Defective high pressure
control.
c. Low Charge; Low pressure
switch open.
d. Defective reset relay
contact.
Check for the following:
a. Defective compressor
contactor.
b. Improper wiring.
c. Reset relay open.
d. Low pressure control open.
e. Cooling relay not
energized. Defective relay;
check thermostat circuit.
See probable cause #2
above.
See "Compressor Motor
Winding Stat Open".
a. Check compressor amp
draw.
Symptom
B. Compressor hums, but will not start.
Probable Cause
1. Low voltage at
compressor.
2. Defective compressor. Check for the following:
3. Insufficient starting
voltage (Single-phase
units only)
Symptom
C. 2nd stage compressor fails to start.
Probable Cause
1. Time delay contacts
fail to close.
2. No call for cooling.
3. Unit locked out by
reset relay.
4. Compressor contactor See Symptom A, Probable
will not close.
(Continued on next page)
Recommended Action
Check for the following:
a. Single blown fuse.
b. Low line voltage.
c. Defective compressor
contactor.
d. Loose wiring
connections.
a. Open motor winding.
b. Excessive amp draw on
all phases.
Check for the following:
a. Defective start capacity.
b. Defective start relay.
Recommended Action
Replace time delay relay.
Check for the following:
a. Defective thermostat.
b. Broken or improper
control wiring.
See Symptom A, Probable
Cause #4.
Cause #5.
61
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