American Standard Blower Stuck On

The indoor blower runs continuously even when the 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 the thermostat, stuck fan relay on the control board, open limit switch forcing the fan on, short between R and G on the American Standard control.

How to Fix / Troubleshooting

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 the G wire at the furnace; if the blower stops, the thermostat or wiring is calling for the fan.
  • If the blower still runs with G removed and limits closed, the control board fan relay is likely stuck, and the board should be replaced.
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Repair Difficulty

Medium 3/5

Required Part

Integrated Furnace Control Board
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