Furnace will not start at all; no lights or display; blower and inducer off.

Safety first: Before resetting breakers, ensure there is no burning smell or visible damage at the furnace.

• Step 1 – Check breaker: Locate the furnace breaker in the electrical panel. If tripped, reset once by switching fully OFF then ON. If it trips again, do not continue resetting; call a professional.
• Step 2 – Verify service switch: Ensure the furnace service switch (often looks like a light switch near the unit) is ON.
• Step 3 – Check blower door: Make sure the blower door is properly installed and depressing the door safety switch. The furnace will not power up if the door is loose.
• Step 4 – Inspect board fuse: With power off, remove the blower door and check the low-voltage fuse on the Ducane control board. Replace with the same rating if blown, but investigate for shorts in thermostat wiring.
• Step 5 – Call a technician: If power is present at the furnace disconnect but the board remains dead, the control board or transformer may have failed.