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Problem Possible Cause Possible Solution
Possible Solution
Possible Solution
Possible Solution
Possible Solution
Unit does not run
Power disconnected. Check power source.
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.
Loose or disconnected wiring at
switch.
Check wiring & connections. Connect per wiring
diagram.
Inoperative switch (On-Off).
Test for continuity, 3 and 2, 5 and 6. If bad,
replace.
Problem Possible Cause
Evaporator coil
freezes up
Dirty filter. Clean as recommended in Owner's Manual.
Restricted airflow.
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 fan motor & replace if inoperative.
Problem Possible Cause
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.
Incorrect thermostat setting. Set to correct setting.
Problem Possible Cause
Thermostat
does not turn on
compressor
Loss of charge in thermostat bulb. Replace thermostat.
Thermostat contacts open.
Test for continuity at terminals 1 and 2. Replace if
defective.
Incorrect wiring or loose wires. Connect per wiring diagram. Tighten loose wires.
System switch open. Test for continuity at switch terminals 2 and 3.
Problem Possible Cause
Thermostat
does not turn off
compressor
Thermostat set at coldest point Adjust.
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.
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