Furnace is completely dead; no lights, no blower, no response to thermostat.

Safety: Use caution when working around line voltage. Turn off power at the breaker before opening electrical compartments.

• Breaker and switch: Check the furnace circuit breaker in the electrical panel and reset if tripped. Verify the furnace service switch (often on or near the unit) is ON.
• Door switch: Ensure the blower door is properly installed and depressing the door safety switch.
• Internal fuse: Inspect the low-voltage fuse on the Wolf control board and replace if blown, after checking for shorts.
• Wiring connections: Inspect the line-voltage junction box on the furnace for loose or burned connections. Tighten or repair as needed.