E7
Ducane
Stuck Fan Relay or Fan Control Fault
E7 code, blower runs continuously even with thermostat off, no heat
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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
Failed blower relay on Ducane control board, Shorted G (fan) thermostat wire to R, Miswired thermostat fan setting, Faulty integrated furnace control
How to Fix / Troubleshooting
Safety first: Turn off power to the furnace before accessing the control board or thermostat wiring.
- Step 1 – Check thermostat fan setting: Ensure the thermostat fan mode is set to AUTO, not ON. If set to ON, the blower will run continuously by design.
- Step 2 – Inspect G wire: Remove the thermostat from its base and inspect the G (green) wire. Make sure no bare copper is touching other terminals. At the furnace control board, verify the G wire is not shorted to R or other terminals.
- Step 3 – Power cycle: Turn power off for 5 minutes, then restore. If the blower immediately starts without a call for heat or cool, the blower relay on the Ducane IFC may be stuck closed.
- Step 4 – Check for error LEDs: Some Ducane boards use LED flash codes in addition to E-codes. Note any patterns and consult the service label.
- Step 5 – Board replacement: If wiring and thermostat are correct and the blower relay is stuck, the control board will likely need replacement by a professional.
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Repair Difficulty
Hard
4/5
Required Part
Ducane Integrated Furnace Control Board
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