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TROUBLESHOOTING
Unit Troubleshooting
Refer to Tables 11 and 12 for troubleshooting
details.
Table 11 - Cooling
Service
Analysis
PROBLEM
CAUSE
REMEDY
Compressor
and
Power failure.
Call power company.
Condenser
Fan
Fuse blown or circuit breaker tripped.
Replace fuse or reset circuit breaker.
Will Not Start.
Defective thermostat, contactor, transformer, or control
Replace component.
relay.
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
Faulty wiring or loose connections
in compressor
cir-
Check wiring and repair or replace.
Start but Condenser
Fan
cult.
Runs.
Compressor
motor burned out, seized, or internal
Determine cause. Replace compressor.
overload open.
Defective overload.
Determine cause and replace.
Compressor
locked out
Determine cause for safety trip and reset lockout.
One leg of 3-phase power dead.
Replace fuse or reset circuit breaker.
Determine cause.
Compressor
Cycles
Refrigerant overcharge or undercharge.
Recover refrigerant, evacuate system, and recharge
(other than normally
to nameplate.
satisfying thermostat).
Defective compressor.
Replace and determine cause.
Insufficient line voltage.
Determine cause and correct.
Blocked condenser.
Determine cause and correct.
Defective overload.
Determine cause and replace.
Defective thermostat.
Replace thermostat.
Faulty condenser-fan
motor.
Replace.
Restriction in refrigerant system.
Locate restriction and remove.
Compressor
Operates
Dirty air filter.
Replace filter.
Continuously.
Unit undersized for load.
Decrease load or increase unit size.
Thermostat
set too low.
Reset thermostat.
Low refrigerant charge.
Locate leak, repair, and recharge.
Air in system.
Recover refrigerant, evacuate system, and recharge.
Condenser coil dirty or restricted.
Clean coil or remove restriction.
Excessive
Head
Dirty air filter.
Replace filter.
Pressure.
Dirty condenser coil.
Clean coil.
Refrigerant overcharged.
Recover excess refrigerant.
Faulty TXV.
1. Check TXV bulb mounting and secure tightly to
suction line.
2. Replace TXV if stuck open or closed.
Air in system.
Recover refrigerant, evacuate system, and recharge.
Condenser air restricted or air short-cycling.
Determine cause and correct.
Head Pressure
Too Low.
Low refrigerant charge.
Check for leaks, repair, and recharge.
Restriction in liquid tube.
Remove restriction.
Excessive
Suction
High heat load.
Check for source and eliminate.
Pressure.
Faulty TXV.
1. Check TXV bulb mounting and secure tightly to
suction line.
2. Replace TXV if stuck open or closed.
Refrigerant overcharged.
Recover excess refrigerant.
Suction
Pressure
Too
Dirty air filter.
Replace filter.
Low.
Low refrigerant charge.
Check for leaks, repair, and recharge.
Metering device or low side restricted.
Remove source of restriction.
Faulty TXV.
1. Check TXV bulb mounting and secure tightly to
suction line.
2. Replace TXV if stuck open or closed.
Insufficient evaporator airflow.
Increase air quantity. Check filter and replace if
necessary.
Temperature too low in conditioned
area.
Reset thermostat.
Field-installed filter drier restricted.
Replace.
LEGEND
TXV - Thermostatic
Expansion Valve
44
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