Ruud
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 switch on thermostat set to ON, Stuck fan relay on control board, Open limit switch causing safety fan operation, Shorted G to R on low-voltage wiring
How to Fix / Troubleshooting
Safety: Turn off power before accessing the control board or thermostat wiring.
Steps to check:
- Thermostat setting: Verify the fan setting is AUTO, not ON.
- Check for G-R short: At the furnace, disconnect the G wire from the control board. If the blower stops, the thermostat or cable is calling for fan. If it continues, the issue is in the furnace.
- Inspect limit switch: If the high limit is open, some Ruud furnaces run the blower continuously for safety. Check for a dirty filter or overheating condition.
- Fan relay: If the blower runs with no call and limits are closed, the fan relay on the control board may be stuck, requiring board replacement.
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Repair Difficulty
Medium
3/5
Required Part
Integrated Furnace Control Board
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