TABLE 14—TROUBLESHOOTING CHART
SYMPTOM
CAUSE
REMEDY
Compressor and outdoor 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, defrost board, or high pressure or loss-
of-charge/low pressure switch
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
Compressor will not start but condenser 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
Low input voltage (20 percent low)
Determine cause and correct
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
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 restricted or air short-cycling
Determine cause and correct
TABLE 14—TROUBLESHOOTING CHART (CONT’D)
SYMPTOM
CAUSE
REMEDY
Head pressure too low
Low refrigerant charge
Check for leaks, repair and recharge
Restriction in liquid tube
Remove restriction
Excessive suction pressure
(Heat) Outdoor coil frosted
Move timer on control board to 30 minutes
between defrost cycles
(Cool) High Heat load
Check for source and eliminate
Reversing valve hung up or leaking internally
Replace valve
Refrigerant overcharged
Recover excess refrigerant
Suction pressure too low
(Cool) Dirty air filter
Replace filter
(Heat) Outdoor coil frosted
Move timer on control board to 30 minutes
between defrost cycles
Low refrigerant charge
Check for leaks, repair and recharge
Metering device or low side restricted
Remove source of restriction
(Cool) Insufficient coil airflow
Increase air quantity
Check filter–replace if necessary
(Cool) Temperature too low in conditioned area
Reset thermostat
(Cool) Outdoor ambient below 40°F
Install low-ambient kit
Filter-drier restricted
Replace
Compressor runs but
outdoor fan does not
NC (normally closed) contacts on defrost board
open
Check condition of relay on board
Replace if necessary
IFM does not run
Blower wheel not secured to shaft
Properly tighten blower wheel to shaft
Insufficient voltage at motor
Determine cause and correct
Power connectors not properly sealed
Connectors should snap easily; do not force
IFM operation is intermittent
Water dripping into motor
Verify proper drip loops in connector wires
Connectors not firmly sealed
Gently pull wires individually to be sure they are
crimped into the housing
IFM (048–060) runs when
it should be off
Motor programmed with a delay profile
Allow a few minutes for motor to shut off
With thermostat in “off” mode, the voltage on
G, Y1, Y2, W with respect to common, should be
1/2 of actual low voltage supply
If measured voltage is more that 1/2, the thermostat
is incompatible with motor. If voltage is less than
1/2, the motor has failed
IFM–Indoor Fan Motor
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