Payne
Fan Control Misconfiguration or Wiring Fault
Thermostat fan setting does not work as expected; fan runs continuously even when set to AUTO, or never runs in ON mode.
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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
G wire miswired or shorted to R, Fan control set to equipment instead of thermostat (or vice versa), Failed fan relay on Payne control board, Stuck G output on thermostat
How to Fix / Troubleshooting
Safety first: Turn off power to the furnace/air handler before working on wiring.
- Check fan mode: Confirm the thermostat is set to AUTO or ON as desired and that any circulation or fan‑only features are configured correctly.
- Inspect G wiring: Ensure the G wire is only connected to the G terminal at both thermostat and control board and not touching R or other terminals.
- Test fan relay (advanced): Remove the G wire at the control board. If the fan continues to run with G disconnected, the Payne control board relay may be stuck closed and needs replacement.
- Bypass thermostat: With power off, jumper R to G at the control board. Restore power; if the fan does not run, the board or blower motor circuit is faulty.
- Replace thermostat: If the fan behaves normally when controlled directly at the board but not via the thermostat, replace the thermostat.
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Repair Difficulty
Medium
3/5
Required Part
Payne Furnace/Air Handler Control Board
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