Troubleshooting Cooling System - Carrier 50FC 04 Series Service And Maintenance Instructions

Troubleshooting Cooling System

Refer to Table 3 for additional troubleshooting topics.
SYMPTOM
Compressor and Outdoor
Fan Will Not Start
Compressor Will Not Start
but Outdoor Fan Runs
Compressor Cycles (Other
Than Normally Satisfying
Thermostat)
Compressor Operates
Continuously
Compressor Makes
Excessive Noise
Excessive Head Pressure
Head Pressure Too Low
Excessive Suction Pressure
Suction Pressure Too Low
Table 3 — Troubleshooting
CAUSE
Power failure.
Fuse blown or circuit breaker tripped.
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.
Faulty wiring or loose connections in compressor
circuit.
Compressor motor burned out, seized, or internal
overload open.
Defective run/start capacitor, overload, start
relay.
One leg of 3-phase power dead.
Refrigerant overcharge or undercharge.
Defective compressor.
Insufficient line voltage.
Blocked outdoor coil or dirty air filter.
Defective Run/Start capacitor, overload, start
relay.
Defective thermostat.
Faulty outdoor-fan (cooling) or indoor-fan
(heating) motor or capacitor.
Restriction in refrigerant system.
Defective loader plug.
Dirty air filter.
Unit undersized for load.
Thermostat set too low (cooling).
Low refrigerant charge.
Air in system.
Outdoor coil dirty or restricted.
Compressor rotating in the wrong direction.
Dirty outside.
Dirty outdoor coil (cooling).
Refrigerant overcharged.
Air in system.
Condensing air restricted or air short-cycling.
Low refrigerant charge.
Compressor scroll plates defective.
Restriction in liquid tube.
High heat load.
Compressor scroll plates defective.
Refrigerant overcharge.
Dirty air filter (cooling).
Dirt 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 temperature below 40°F
(cooling).
Outdoor fan motor(s) not operating (heating).
Call power company.
Replace fuse or reset circuit breaker. Determine root cause.
Replacement 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. Replace compressor or allow enough time for
internal overload to cool and reset.
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 correct.
Replace thermostat.
Replace faulty part.
Locate restriction and remove.
Determine cause and replace.
Replaced 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.
20
SOLUTION