Safety: Disconnect power before removing the combustion chamber cover. Do not run the unit with the fan housing open.

1. Listen for fan start: On a call for heat, the fan should start before ignition. If it is silent, suspect a fan or power supply issue.
2. Access fan: Remove the front panel and combustion cover to access the ACV fan assembly.
3. Check for obstructions: Inspect the fan wheel for debris, insulation, or broken plastic pieces. Remove any foreign objects carefully.
4. Spin test: With power off, gently spin the fan wheel by hand. It should rotate freely. If stiff or seized, the fan must be replaced.
5. Electrical checks: Verify the fan connector is fully seated on the control board and at the fan. Check for signs of overheating or melted plastic.
6. Voltage test (qualified personnel): With the unit calling for heat, measure voltage at the fan terminals. If correct voltage is present but the fan does not run, replace the fan. If no voltage, suspect the control board.

Fan replacement involves working on the combustion circuit and should be carried out by an ACV-trained technician.

Display shows E08, unit does not start, fan may not run

Possible Causes