3-2
INDICATION/
REFERENCE
TROUBLE
POSSIBLE CAUSES
SECTION
3.4 UNIT WILL NOT HEAT OR HAS INSUFFICIENT HEATING
No power to unit
Start-Stop switch OFF or defective
Check
Circuit breaker OFF or defective
Check
External power source OFF
Turn on
No control power
Circuit breaker or fuse defective
Replace
Transformer defective (TR)
Replace
Evaporator fan internal motor protector open
4.15
Heat relay defective
Check
Heater termination switch open
4.14
Unit will not heat or
Heater(s) defective
4.16
has insufficient heat
Heater contactor or coil defective
Replace
Evaporator fan motor(s) defective or rotating backwards
4.15/4.27
Evaporator fan motor contactor defective
Replace
Temperature controller malfunction
3.9
Defective wiring
Replace
Loose terminal connections
Tighten
Low line voltage
1.5
3.5 UNIT WILL NOT TERMINATE HEATING
Unit fails to stop
Temperature controller improperly set
Reset
heating
Temperature controller malfunction
3.9
Heater termination switch remains closed along with the
heat relay
4.14
3.6 UNIT WILL NOT DEFROST PROPERLY
Will not initiate
Defrost timer malfunction
1.12.5
defrost automatically
Loose terminal connections
Tighten
Defective wiring
Replace
Defrost termination sensor defective
or heat termination switch open
Replace
Heater contactor or coil defective
Replace
Will not initiate
Manual defrost switch defective
Replace
defrost manually
Defrost termination sensor open
2.4.4
Initiates but relay
(DR) drops out
Low line voltage
1.5
Initiates but does not
Heater contactor or coil defective
Replace
defrost
Heater(s) burned out
4.16
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