Heil Blower Stuck On

Indoor blower runs continuously even when thermostat is not calling for heat or fan.

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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 set to ON at thermostat, Stuck blower relay on control board, Open limit switch causing fan-only mode, Shorted G (fan) thermostat wire to R

How to Fix / Troubleshooting

Safety: Turn off power before accessing control board or wiring.

Steps to check:

  • Thermostat fan setting: Ensure the fan is set to AUTO, not ON.
  • Check thermostat wiring: At the furnace board, disconnect the G wire. Restore power. If the blower stops, the thermostat or wiring is calling for fan.
  • Inspect limit switch: If the main limit is open, many Heil furnaces will run the blower continuously. Check for an error code indicating limit open and correct overheating causes.
  • Control board relay: If blower runs with G disconnected and no limit fault, the blower relay on the board may be stuck closed.

When to call a pro: A technician should replace the control board if the blower relay is welded, and verify limit circuit operation.

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Repair Difficulty

Medium 3/5

Required Part

Furnace Control Board
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