5. Heater blowing cold air with
* High-limit switch open.
* See Problem Number 6.
pilot light burning.
* Defective solenoid in gas control valve.
* Replace gas control valve.
* Burner orifice plugged.
* Clean orifice with compressed air.
* Throat of burner casting plugged.
* Clean burner throat with compressed air.
6. High limit switch open.
* Defective high limit switch.
* Replace high limit switch.
* Wrong gas type, pressure too high,
* Check the dataplate on heater for
liquid propane in gas line due to
correct type of gas and the operating
improper regulation and/or line size.
pressure. Correct as necessary.
* Loose fan wheel.
* Tighten fan wheel.
* Dirty fan wheel.
* Clean fan wheel.
* Motor overheating and
* Thermal overload switch in
shutting off.
motor opening due to:
a.
Low voltage-check voltage supply
against unit voltage requirements.
b.
Dirty motor-clean motor housing.
* Blockage at blower outlet or inlet.
* Remove blockage.
* Defective high-limit heat switch.
* Replace high-limit heat switch.
7. Main burner does not shut
* Defective gas valve.
* Replace gas valve.
off when temperature requirement
is satisfied.
* Defective thermostat.
* Replace thermostat.
8. Gas valve "chatters".
* Defective solenoid in gas valve.
* Replace gas valve.
* Gas pressure too high.
* Check nameplate on heater for correct
type of gas and operating pressure.
* Improper voltage.
* Check voltage supply against
unit voltage requirements.
9. Motor “hums”
* Defective capacitor.
* Replace capacitor.
* Wires disconnected between motor
* Reconnect wires accordingly
and capacitor.
and test for proper operation.
10. Motor does not run.
* No voltage from thermostat to motor.
* Check for voltage at power supply.
Repair as necessary.
* Defective thermostat.
* Replace thermostat.
* Defective capacitor.
* Replace capacitor.
* Defective motor.
* Replace motor.
(1) With any electrical problem, all wiring should be checked for good connections and proper voltage and repaired if a problem is
found.
(2) To determine if part is defective, place a jumper wire across the two terminals that the wires are connected to. Use the jumper wire
only to determine if part is defective. Replace the part IMMEDIATELY or do not operate unit until properly serviced. NEVER
operate a heater with safety device bypassed.
(3) The high-limit switch will open or “trip” for a variety of reasons including high fuel pressure (see nameplate or owner’s manual for
proper pressures) or reduced air flow. Reduced air flow is normally due to intake air obstructions, low voltage or dirty fan wheels,
etc.
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