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TROUBLESHOOTING
I. UNIT TROUBLESHOOTING
Refer to Tables 30-32 for additional information.
Table 30 — Cooling Troubleshooting
PROBLEM CAUSE REMEDY
Compressor(s) 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.
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.
High pressure switch tripped. See problem “Excessive Head Pressure.”
Low pressure switch tripped. Check system for leaks, repair, and recharge.
Freeze-up protection thermostat tripped. See problem “Suction Pressure Too Low.”
Compressor(s) Will Not
Start but Condenser Fan
Runs.
Faulty wiring or loose connections in compressor
circuit.
Check wiring and repair or replace.
Compressor motor(s) burned out, seized, or internal
overload open.
Determine cause. Replace compressor(s).
Defective overload. Determine cause and replace.
One leg of 3-phase power dead. Replace fuse or reset circuit breaker. Determine cause.
Compressor(s) Cycles
(Other Than Normally
Satisfying Thermostat).
Refrigerant overcharge or undercharge. Recover 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 overload. Determine cause and replace.
Defective thermostat. Replace thermostat.
Faulty condenser-fan motor(s) or capacitor. Replace.
Restriction in refrigerant system. Locate restriction and remove.
Compressor(s) 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. Recover refrigerant, evacuate system, and recharge.
Condenser coil dirty or restricted. Clean coil or remove restriction.
Scroll Compressor(s)
Makes Excessive Noise.
Compressor(s) rotating in the wrong direction. Reverse the 3-phase power leads as described in
Start-Up section, page 38.
Excessive Head Pressure. Dirty air filter. Replace filter.
Dirty condenser coil. Clean coil.
Refrigerant overcharged. Remove excess refrigerant.
Air in system. Recover refrigerant, evacuate system to 500 microns,
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(s).
Restriction in liquid tube. Remove restriction.
Excessive Suction
Pressure.
High heat load. Check for source and eliminate.
Compressor valves leaking. Replace compressor(s).
Refrigerant overcharged. Recover excess refrigerant.
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.
Field-installed filter drier restricted. Replace.
Outdoor ambient temperature below 25 F. Install low-ambient kit.
Compressor No. 2
Will Not Run.
Unit in economizer mode. Proper operation; no remedy necessary.