Carrier 50TCQ 04 Series Service And Maintenance Instructions page 22

PROBLEM
Compressor and Power failure.
Outdoor Fan
Fuse blown or circuit breaker tripped.
Will Not Start.
Defective thermostat, contactor, transformer,
control relay, or capacitor.
Insufficient line voltage.
Incorrect or faulty wiring.
Thermostat setting too high.
High pressure switch tripped.
Low pressure switch tripped.
Freeze‐up protection thermostat tripped.
Compressor Will Not Faulty wiring or loose connections in compressor
Start But Outdoor circuit.
Fan Runs.
Compressor motor burned out, seized, or
internal overload open.
Defective run/start capacitor, overload, start
relay.
One leg of 3‐phase power dead.
Compressor Cycles Refrigerant overcharge or undercharge.
(Other Than
Defective compressor.
Normally Satisfying
Insufficient line voltage.
Thermostat).
Blocked outdoor coil or dirty air filter.
Defective run/start capacitor, overload, or start
relay.
Defective thermostat.
Faulty outdoor‐fan (cooling) or indoor‐fan
(heating) motor or capacitor.
Restriction in refrigerant system.
Compressor Operates Dirty air filter.
Continuously.
Unit undersized for load.
Thermostat set too low (cooling).
Low refrigerant charge.
Air in system.
Outdoor coil dirty or restricted.
Compressor Makes Compressor rotating in the wrong direction.
Excessive Noise.
Excessive Head Dirty outside air or return air filter (heating).
Pressure.
Dirty outdoor coil (cooling).
Refrigerant overcharged.
Air in system.
Condensing air restricted or air short‐cycling.
Head Pressure Low refrigerant charge.
Too Low.
Compressor scroll plates defective.
Restriction in liquid tube.
Excessive Suction High heat load.
Pressure.
Compressor scroll plates defective.
Refrigerant overcharged.
Suction Pressure Dirty air filter (cooling).
Too Low.
Dirty or heavily iced outdoor coil (heating).
Low refrigerant charge.
Metering device or low side restricted.
Insufficient indoor airflow (cooling mode).
Temperature too low in conditioned area.
Field‐installed filter drier restricted.
Outdoor ambient below 25_F (cooling).
Outdoor fan motor(s) not operating (heating).
Table 6 –
Heating and Cooling Troubleshooting
CAUSE
Call power company.
Replace fuse or reset circuit breaker. Determine root cause.
Replace component.
Determine cause and correct.
Check wiring diagram and rewire correctly.
Lower thermostat setting below room temperature.
See problem ``Excessive head pressure.''
Check system for leaks. Repair as necessary.
See problem ``Suction pressure too low.''
Check wiring and repair or replace.
Determine cause. Replace compressor or allow enough time for
internal overload to cool and reset.
Determine cause and replace compressor.
Replace fuse or reset circuit breaker. Determine cause.
Recover refrigerant, evacuate system, and recharge to nameplate.
Replace and determine cause.
Determine cause and correct.
Determine cause and correct.
Determine cause and replace.
Replace thermostat.
Replace.
Locate restriction and remove.
Replace filter.
Decrease load or increase unit size.
Reset thermostat.
Locate leak; repair and recharge.
Recover refrigerant, evacuate system, and recharge.
Clean coil or remove restriction.
Reverse the 3‐phase power leads as described in
Start‐Up.
Replace filter.
Clean coil.
Recover excess refrigerant.
Recover refrigerant, evacuate system, and recharge.
Determine cause and correct.
Check for leaks; repair and recharge.
Replace compressor.
Remove restriction.
Check for source and eliminate.
Replace compressor.
Recover excess refrigerant.
Replace filter.
Clean outdoor coil. Check defrost cycle operation.
Check for leaks; repair and recharge.
Remove source of restriction.
Increase air quantity. Check filter and replace if necessary.
Reset thermostat.
Replace.
Install low‐ambient kit.
Check fan motor operation.
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REMEDY