Carrier 38AF Series Installation Manual page 12

12
Problem
COMPRESSOR DOES NOT RUN
Contractor Open
1. Power off.
2. Fuses blown in field power circuit.
3. No control power.
4. Thermostat circuit opens.
5. Time Guard ll device not operating.
6. Compressor circuit breaker tripped.
7. Safety device lock-out circuit
active.
8. Low-pressure switch opens.
9. High-pressure switch open.
10. Compressor over temperature
switch open.
11. Loose electrical connections.
12. Compressor stuck.
Contractor Closed
1. Compressor leads loose.
2. Motor windings open.
3. Single phasing.
COMPRESSOR STOPS ON HIGH-
PRESSURW SWITCH
Outdoor Fan On
1. High-pressure switch faulty.
2. Reversed fan rotation
3. Airflow restricted.
4. Air recalculating.
5. Non condensable in system.
6. Refrigerant overcharge.
7. Line voltage incorrect.
8. Refrigerant system restrictions.
Outdoor Fan Off
1. Fan slips on shaft.
2. Motor not running.
3. Motor bearings stuck.
4. Motor overload open.
5. Motor burned out.
COMPRESSOR CYCLES ON LOW-
PRESSURE SWITCH
Indoor-Air Fan Running
1. Compressor suction service valve
partially closed.
2. Liquid line solenoid valve(s) fails to
open.
3. Filter drier plugged.
4. Expansion valve power head
defective.
5. Low refrigerant charge.
TROUBLESHOOTING PROBLEM
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10. Check for open condition. Allow for reset. Replace
11. Tighten all connections.
12. See compressor service literature.
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Solution
Restore power.
After finding cause and correcting. Replace with
correct size fuse.
Check secondary fuse(s); replace with correct type
and size.
Check thermostat setting.
Check Time Guard ll devices.
Check for excessive compressor current draw.
Reset breaker; replace if defective.
Reset lockout circuit at thermostat or circuit
breaker.
Check for refrigerant undercharge, obstruction of
indoor airflow, or whether compressor suction
shutoff valve is fully open. Be sure outdoor fans
are operating correctly.
Check for refrigerant overcharge, obstruction of
outdoor airflow, air in system. or whether
compressor discharge valve is fully open. Be sure
outdoor fans are operating correctly.
if defective.
Check connections
See compressor service literature.
Check for blown fuse. Check for loose connection
at compressor terminal.
Replace switch.
Confirm rotation, correct if necessary.
Remove obstruction.
Clear airflow area.
Purge and recharge as required.
Purge as required.
Consult Power Company.
Check or replace filter drier, expansion valve, etc.
Check that compressor discharge service valve is
fully open.
Tighten fan hub set screws.
Check power and capacitor.
Replace bearings.
Check overload rating. Check for fan blade
obstruction.
Replace motor.
Open valve fully.
Check liquid line solenoids valve (s) for proper
operation Replace if necessary.
Replace filter drier.
Replace power head.
Add charge. Check low-pressure switch setting.