Carrier 50ZH024-060 - Manual (Page 18)

TROUBLESHOOTING
Cooling and Heating Troubleshooting Chart
SYMPTOM CAUSE REMEDY
Compressor and out-
door fan will not start. Power failure Call power company.
Fuse blown or circuit breaker tripped Replace fuse or reset circuit breaker.
Defective thermostat, contactor, transformer,
control relay, or defrost board Replace component.
Insufficient line voltage Determine cause and correct.
Incorrect or faulty wiring Check wiring diagram and rewire correctly.
Thermostat setting too high Lower thermostat setting below room temperature.
Units have a 5-minute time delay DO NOT bypass this compressor time delay — wait
for 5 minutes until time-delay relay is deenergized.
Compressor will not
start but outdoor fan
runs. Faulty wiring or loose connections in
compressor circuit Check wiring and repair or replace.
Compressor motor burned out, seized, or
internal overload open Determine cause. Replace compressor.
Defective run capacitor, overload,
or PTC (positive temperature coefficient)
thermistor Determine cause and replace.
One leg of 3-phase power dead Replace fuse or reset circuit breaker.
Determine cause.
Low input voltage (20% low) Determine cause and correct.
Three-phase scroll
compressor
(size 036-060
units only) makes ex-
cessive noise, and
there may be a low
pressure differential Scroll compressor is rotating in the
wrong direction Correct the direction of rotation by reversing the
3-phase power leads to the unit.
Compressor cycles
(other than normally
satisfying thermostat). Refrigerant overcharge or undercharge Recover refrigerant, evacuate system, and recharge
to capacities shown on nameplate.
Defective compressor Replace and determine cause.
Insufficient line voltage Determine cause and correct.
Blocked outdoor coil Determine cause and correct.
Defective run/start capacitor, overload,
or start relay Determine cause and replace.
Defective thermostat Replace thermostat.
Faulty outdoor-fan motor or capacitor Replace.
Damaged reversing valve Determine cause and correct.
Restriction in refrigerant system Locate restriction and remove.
Compressor operates
continuously. Dirty air filter Replace filter.
Unit undersized for load Decrease load or increase unit size.
Thermostat set too low Reset thermostat.
Low refrigerant charge Locate leak, repair and recharge.
Leaking valves in compressor Replace compressor.
Frosted coil with incorrect defrost operation Check defrost time settings. Reset as necessary.
Check defrost temperature switch. Replace as necessary.
Air in system Recover refrigerant, evacuate system, and recharge.
Outdoor coil dirty or restricted Clean coil or remove restriction.
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