American Standard Blower Stuck On

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

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 set to ON at thermostat, Stuck fan relay on control board, Open limit switch forcing fan on, Short between R and G on American Standard control

Safety: Turn off power before touching wiring.

Check thermostat:
- Set fan to AUTO and system to OFF; wait several minutes.
Inspect limit switch:
- If the primary limit is open, the board may run the fan continuously. Address overheating causes.
Check G circuit:
- Disconnect G wire at furnace; if blower stops, the thermostat or wiring is calling for fan.
If blower still runs with G removed and limits closed, the control board fan relay is likely stuck and the board should be replaced.

Medium 3/5

Integrated Furnace Control Board

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