Furnace will not start at all; no lights on the control board, no blower or inducer operation.

Safety: If you are not comfortable working with 120V circuits, contact a professional.

• 1. Check breaker: Locate the furnace circuit breaker in your electrical panel and reset it if tripped. If it trips again, stop and call a technician.
• 2. Verify service switch: Ensure the furnace service switch (often looks like a light switch near the unit) is in the ON position.
• 3. Inspect door switch: Confirm the blower door is properly installed and depressing the door safety switch.
• 4. Internal fuse: With power off, inspect the control board fuse and replace it if blown. If it blows again, there is a short that needs professional diagnosis.