Carrier WeatherMaker 50KCQ A04 Series Service And Maintenance Instructions page 19

PROBLEM
Power failure.
Fuse blown or circuit breaker tripped.
Defective thermostat, contactor, transformer, control
relay, or capacitor.
Compressor and
Insufficient line voltage.
outdoor fan will
Incorrect or faulty wiring.
not start
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 will
Compressor motor burned out, seized, or internal
not start
overload open.
but outdoor fan
runs
Defective run/start capacitor, overload, start relay.
One leg of 3-phase power dead.
Refrigerant overcharge or undercharge.
Defective compressor.
Insufficient line voltage.
Compressor
Blocked outdoor coil or dirty air filter.
cycles (other
than normally
Defective run/start capacitor, overload, or start relay. Determine cause and replace.
satisfying
Defective thermostat.
thermostat)
Faulty outdoor-fan (cooling) or indoor-fan (heating)
motor or capacitor.
Restriction in refrigerant system.
Dirty air filter.
Unit undersized for load.
Compressor
Thermostat set too low (cooling).
operates
Low refrigerant charge.
continuously
Air in system.
Outdoor coil dirty or restricted.
Compressor
makes Compressor rotating in the wrong direction.
excessive noise
Dirty outside air or return air filter (heating).
Dirty outdoor coil (cooling).
Excessive head
Refrigerant overcharged.
pressure
Air in system.
Condensing air restricted or air short-cycling.
Low refrigerant charge.
Head pressure
Compressor scroll plates defective.
too low
Restriction in liquid tube.
High heat load.
Excessive suction
Compressor scroll plates defective.
pressure
Refrigerant overcharged.
Dirty air filter (cooling).
Dirty or heavily iced outdoor coil (heating).
Low refrigerant charge.
Metering device or low side restricted.
Suction
pressure Insufficient indoor airflow (cooling mode).
too low
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.
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 (page 55).
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