York Continuous Fan Operation

Furnace blower never shuts off, even when thermostat is satisfied and set to AUTO.

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.

Possible Causes

Fan switch on thermostat set to ON, Stuck blower relay on control board, High limit switch open, Shorted G wire

Safety: Turn off power before working on wiring.

Thermostat setting: Confirm fan is set to AUTO, not ON.
Check limit switch: If the high limit is open, many York furnaces will run the blower continuously. Investigate and correct overheating causes (filter, airflow).
Test G circuit: Remove the G wire from the furnace board. If the blower stops, the thermostat or wiring is calling for fan. If it continues, the board relay is likely stuck.
Board replacement: A stuck blower relay requires replacing the integrated control board.

Medium 3/5

Integrated Furnace Control Board

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