Wyze
Fan Control Misconfiguration or Stuck Relay
Thermostat fan runs continuously even when not calling for heating or cooling.
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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
Fan mode set to On instead of Auto in Wyze app, G wire shorted to R at furnace or thermostat, Stuck fan relay on furnace control board, Miswired Wyze C-Wire Adapter on G circuit
How to Fix / Troubleshooting
Safety first: Turn off furnace power at the breaker before inspecting wiring.
- Check fan mode: On the thermostat or in the Wyze app, ensure the fan mode is set to Auto, not On or Circulate.
- Inspect G wiring: At both the thermostat wall plate and furnace control board, ensure the G wire is not touching R or any other terminal.
- Test for stuck relay (advanced): With power off, disconnect the G wire at the furnace board. Restore power. If the fan still runs, the fan relay on the control board is likely stuck and the board may need replacement.
- Check C-Wire Adapter wiring: If using the Wyze adapter, verify the G connections match the Wyze wiring diagram.
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Repair Difficulty
Hard
4/5
Required Part
Furnace Control Board
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