Lennox Complete Power Loss to Furnace

Furnace will not start at all; no blower, no inducer, no LED lights, but other appliances have power.

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.

Possible Causes

Tripped furnace breaker, Faulty service switch, Loose wiring in furnace junction box, Failed Lennox control board

Safety: Turn off breaker before opening electrical compartments.

1. Check breaker: Reset the furnace breaker once if tripped.
2. Verify service switch: Ensure the furnace switch (often looks like a light switch) is ON.
3. Inspect junction box: Confirm wire nuts are tight and no wires are burned or loose.

If power is present at the furnace but the board is dead, the control board likely needs replacement by a technician.

Hard 4/5

Lennox Integrated Furnace Control Board

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