Rheem
Blower Stuck in Fan-On Mode
Furnace blower runs continuously even when there is no call for heat or fan
Advertisements
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.
Advertisements
Possible Causes
Thermostat fan set to ON, Stuck blower relay on control board, Open limit switch, Shorted G to R thermostat wire
How to Fix / Troubleshooting
Safety first: Turn off power before accessing the control board or thermostat wiring.
- Check thermostat: Ensure the fan setting is on AUTO, not ON.
- Inspect thermostat wiring: At the furnace, verify that the G wire is not shorted to R or touching other terminals.
- Check limit switch: An open high limit can cause the blower to run continuously. Inspect and test the limit as described earlier.
- Board relay: If wiring and limits are good, the blower relay on the control board may be stuck closed, requiring board replacement.
Continuous blower operation increases energy use and may indicate an underlying safety issue.
Advertisements
Repair Difficulty
Medium
3/5
Required Part
Integrated Furnace Control Board
Check Price on Amazon
We may earn a commission from links on this page.
Advertisements