Carrier 50TFQ008-012 Installation, Start-Up And Service Instructions Manual page 52

PROBLEM
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.
Excessive Head Pressure.
Head Pressure Too Low.
Excessive Suction Pressure.
Suction Pressure Too Low.
Compressor No. 2 Will Not Run.
Table 28 — Heating and Cooling Troubleshooting
CAUSE
Power failure.
Fuse blown or circuit breaker tripped.
Defective thermostat, contactor, transformer, or
control relay.
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 overload.
One leg of 3-phase power dead.
Refrigerant overcharge or undercharge.
Defective compressor.
Insufficient line voltage.
Blocked outdoor coil or dirty air filter.
Defective overload.
Defective thermostat.
Faulty outdoor-fan (cooling) or indoor-fan (heating)
motor or capacitor.
Restriction in refrigerant system.
Dirty air filter.
Unit undersized for load.
Thermostat set too low.
Low refrigerant charge.
Leaking valves in compressor.
Air in system.
Outdoor coil dirty or restricted.
Dirty air filter.
Dirty outdoor coil.
Refrigerant overcharged.
Air in system.
Condensing air restricted or air short-cycling.
Low refrigerant charge.
Compressor valves leaking.
Restriction in liquid tube.
High heat load.
Compressor valves leaking.
Refrigerant overcharged.
Dirty air filter (cooling) or dirty 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 25 F.
Unit in economizer mode.
Call power company.
Replace fuse or reset circuit breaker.
Replace component.
Determine cause and correct.
Check wiring diagram and rewire correctly.
Lower thermostat setting below room
temperature.
See problem ''Excessive Head Pressure.''
Check for leaks, repair, and recharge.
See problem ''Suction Pressure Too Low.''
Check wiring and repair or replace.
Determine cause. Replace compressor.
Determine cause and replace.
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.
Replace compressor.
Recover refrigerant, evacuate system, and
recharge.
Clean coil or remove restriction.
Replace filter.
Clean coil.
Remove 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 or clean coil.
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.
Proper operation; no remedy necessary.
52
REMEDY