Thermia
Blower Motor Start Failure
Furnace inducer runs but main blower never starts, causing the furnace to overheat and shut down.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Failed blower motor, Bad blower run capacitor (PSC motor), Loose blower wiring, Faulty blower relay on Thermia control board
How to Fix / Troubleshooting
Safety first: Turn off power before working on the blower assembly.
- 1. Check blower wiring: Inspect the harness from the Thermia control board to the blower motor for loose or burned connectors.
- 2. Test blower in FAN mode: Set thermostat fan to ON. If the blower does not run, suspect the motor, capacitor, or control board.
- 3. Inspect and test capacitor (PSC motors): Remove the capacitor and test with a capacitance meter. Replace with a Thermia-specified capacitor if out of tolerance.
- 4. Spin blower wheel: With power off, spin the wheel by hand. If stiff or seized, replace the blower motor.
- 5. If motor and capacitor test good: The blower relay or control board may be faulty and require replacement.
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Repair Difficulty
Hard
4/5
Required Part
Blower Motor Assembly
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