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TABLE 10—TROUBLESHOOTING — COOLING
SYMPTOM 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,
controlrelay,highpressure,orlossofcharge
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 tempera-
ture.
Compressor will not start but condenser fan
runs.
Faulty wiring or loose connections in compres-
sor circuit
Check wiring and repair or replace.
Compressor motor burned out, seized, or inter-
nal overload open
Determine cause. Replace compressor.
Defective run/start capacitor, overload, start re-
lay
Determine cause and replace.
One leg of 3-phase power dead
Replace fuse or reset circuit breaker. Determine
cause.
Three-phase scroll compressor makes ex-
cessive noise, and there may be a low pres-
sure differential.
Scroll compressor is rotating in the wrong direc-
tion
Correct the direction of rotation by reversing the
3-phase power leads to the unit. Shut down unit
to allow pressures to equalize.
Compressor cycles (other than normally sat-
isfying thermostat).
Refrigerant overcharge or undercharge
Recover refrigerant, evacuate system, and re-
charge to capacities shown on 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
Recover refrigerant, evacuate system, and re-
charge.
Condenser coil dirty or restricted Clean coil or remove restriction.
Excessive head pressure.
Dirty air filter Replace filter.
Dirty condenser coil Clean coil.
Refrigerant overcharged Recover excess refrigerant.
Air in system
Recover refrigerant, evacuate system, and re-
charge.
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.
Excessive suction pressure.
High heat load Check for source and eliminate.
Compressor valves leaking Replace compressor.
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 — replace if
necessary.
Temperature too low in conditioned area Reset thermostat.
Outdoor ambient below 40 F Install low-ambient kit.
Field-installed filter-drier restricted Replace.
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