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TROUBLESHOOTING
PROBLEM POSSIBLE CAUSE TO CORRECT
UNIT DOES NOT RUN.
Power disconnected. Check power source.
System switch in “Off”
position.
Set switch correctly.
Branch circuit fuse blown or
circuit breaker tripped.
Replace fuse, reset breaker. If repeats, check fuse
or breaker size. Check for shorts in unit wiring and
components.
Inoperative system switch. Test for continuity.
Loose or disconnected wiring
at switch.
Check wiring and connections.
Connect per wiring diagram.
Inoperative switch (On-Off). Test for continuity, 3 and 2, 5 and 6.
EVAPORATOR COIL
FREEZES UP.
Dirty Filter. Clean as recommended in Owner’s Manual.
Restricted air fl ow. Check for dirty or obstructed coil - clean as required.
Inoperative thermostat. Test for shorted thermostat or stuck contacts.
Short of refrigerant. De-ice coil and check for leak.
Partially restricted capillary.
De-ice coil. Check temperature differential across coil.
Touch test coil return bends for same temperature. Test for
low running current.
Inoperative fan motor. Test and replace if inoperative.
COMPRESSOR RUNS
CONTINUALLY.
DOES NOT CYCLE
OFF.
Excessive heat load. Test cooling performance of unit. Unit undersized.
Restriction in line.
Check for partially iced coil. Check temperature split
across coil.
Refrigerant leak.
Check for presence of oil on silver soldered connections.
Check for partially iced coil. Check split across coil.
Check for low running amperage.
Thermostat contacts stuck.
Check operation of thermostat. Replace if contacts
remain closed.
THERMOSTAT DOES
NOT TURN UNIT ON.
Loss of charge in thermostat
bulb.
Place jumper across thermostat terminals. If unit
operates, replace thermostat.
Loose or broken parts in
thermostat.
Check as above.
Incorrect wiring. Connect per wiring diagram.
System switch open. Test for continuity at switch terminals 2 and 3.
THERMOSTAT DOES
NOT TURN UNIT OFF.
Thermostat set at coldest
point
Turn to highest temperature setting to see of unit will cycle
off.
Thermostat contacts stuck.
Disconnect power to the unit. Remove cover of thermostat
and check if contact is stuck, if so replace thermostat.
Switch (On - Off) shorted.
Test switch for open contacts at terminals 2 and 3 with
switch in “Off” position.