Napoleon
Control Board Relay or Low-Voltage Control Fault
Thermostat calls for heat but furnace only clicks and never starts inducer or blower
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
Failed relay on control board, Weak 24V transformer, Loose low-voltage connections, Faulty safety switch in series with thermostat circuit
How to Fix / Troubleshooting
Safety first: Turn off power before accessing the control board.
- Check 24V: With power on and caution, measure between R and C on the control board. You should see about 24 VAC. If low or zero, suspect the transformer.
- Inspect wiring: Ensure all low-voltage wires are firmly connected and not corroded.
- Listen for relays: When the thermostat calls for heat, you may hear a faint click from the board. If there is a click but no inducer start, the inducer relay or board output may be faulty.
- Board replacement: If transformer output is good and safeties are closed but the board does not energize the inducer, replace the integrated control board.
Advertisements
Repair Difficulty
Hard
4/5
Required Part
Integrated Furnace Control Board
Check Price on Amazon
We may earn a commission from links on this page.
Advertisements