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.
One leg of 3-phase power dead
Replace fuse or reset circuit breaker.
Determine cause.
Low input voltge (20% low)
Determine cause and correct.
Three-phase scroll
compressor
(size 048 and 060
units only) makes
excessive 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 overload
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.
Excessive head
pressure.
Dirty air filter
Replace filter.
Dirty indoor or outdoor coil
Clean coil.
Refrigerant overcharged
Recover excess refrigerant.
Air in system
Recover refrigerant, evacuate system, and recharge.
(Heat) Indoor air restricted or recirculating
Determine cause and correct.
Indoor or outdoor air inlet restricted
Determine cause and correct.
Head pressure too low.
Low refrigerant charge
Check for leaks, repair and recharge.
Compressor valves leaking
Replace compressor.
Restriction in liquid tube
Remove restriction.
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