Troubleshooting
Symptom
Possible cause
Corrective action
Fan operates but
no heating (electric
heating units)
No power to electric heating
circuit on units with dual point
power.
Establish power to electric heating circuit.
Loose or improper wiring from
thermostat to electric heating
contactor.
Verify all wiring connections and terminations, verify proper wiring of
thermostat.
Loose or improper wiring of
electric
heating element.
Verify all wiring connections and terminations, verify proper wiring of electric
heating element.
Defective electric heating
contactor.
With electric heating contactor energized, verify proper voltage on contactor
load terminals. Replace as required.
Tripped or defective primary
high limit switch.
Turn thermostat to lowest set point and allow fan to run 10-15 minutes for limit
switch to cool and rest. Then turn thermostat to highest set point and check
for proper heating operations. If high limit trips again, check for the following
conditions: improper voltage to heating element; obstructed fan or unit outlet
reducing air flow over heating element; dirty or defective heating element
causing hot spot. If heater does not operate after sufficient time for limit
switch to cool, disconnect power and check continuity across primary high
limit switch. Replace if defective.
Tripped secondary high limit
switch.
Secondary high limit switches are designed to trip only during extreme failure
conditions. Contact factory before attempting any corrective action. Limit
switch will require replacement.
Defective thermostat.
Momentarily jumper thermostat contacts to simulate proper operation.
Replace thermostat as required.
Defective electric heating
element.
Disconnect power and check continuity through
heating element. Replace as required.
Improper aquastat or change
over relay operation on units
so equipped. (Note: electric
heat will not operate when hot
water is present at the unit.)
Verify proper aquastat position on piping, and verify proper aquastat and
change over relay operation.
Replace as required.
Troubleshooting
