Instruction manual
TABLE 7—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
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 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
One leg of 3-phase power dead
Replace fuse or reset circuit breaker. Determine
cause
Low input voltage (20 percent low) Determine cause and correct
Three-phase scroll compressor (size 030-
060 units) 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
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
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–Indoor Fan Motor
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