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Table 20 — Cooling Service Analysis
PROBLEM CAUSE REMEDY
Compressor and
condenser 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 capacitor.
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/start capacitor, overload, start relay. Determine cause and replace.
One leg of of 3-phase power dead. Replace fuse or reset circuit breaker.
Determine cause.
Compressor cycles
(other than normally
satisfying thermostat).
Refrigerant overcharge or undercharge. Reclaim refrigerant, evacuate system, and recharge
to nameplate.
Defective compressor. Replace and determine cause.
Insufficient line voltage. Determine cause and correct.
Blocked condenser. Determine cause and correct.
Defective run/start capacitor, overload, or start relay. Determine cause and replace.
Defective thermostat. Replace thermostat.
Faulty condenser-fan motor or capacitor. Replace.
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.
Air in system. Reclaim refrigerant, evacuate system, and recharge.
Condenser coil dirty or restricted. Clean coil or remove restriction.
Compressor makes
excessive noise.
Compressor rotating in wrong direction. Reverse the 3-phase motor power leads as described in
Start-Up on page 17.
Excessive head pressure. Dirty air filter. Replace filter.
Dirty condenser coil. Clean coil.
Refrigerant overcharged. Reclaim excess refrigerant.
Air in system. Reclaim 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.
Compressor valves leaking. Replace compressor.
Restriction in liquid tube. Remove restriction.
Compressor rotating in wrong direction Reverse the 3-phase motor power leads as described in
Start-Up on page 17.
Excessive suction
pressure.
High heat load. Check for source and eliminate.
Compressor valves leaking. Replace compressor.
Refrigerant overcharged. Reclaim excess refrigerant.
Compressor rotating in wrong direction. Reverse the 3-phase motor power leads as described in
Start-Up on page 17.
Suction pressure too low. Dirty air filter. Replace filter.
Low refrigerant charge. Check for leaks; repair and recharge.
Metering device or low side restricted. Remove source of restriction.
Insufficient evaporator airflow. Increase air quantity. Check filter and replace
if necessary.
Temperature too low in conditioned area. Reset thermostat.
Outdoor ambient below 25 F. Install low-ambient kit.
Evaporator fan
will not shut off.
Time off delay not finished. Wait for 30-second off delay.
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