Furnace will not start at all; no inducer, no blower, no LED lights.

Safety first: Use caution when working around electrical panels. If unsure, contact an electrician.

Steps to check:

• Check breaker: Locate the furnace breaker in the main electrical panel. If tripped, reset once. If it trips again, there is a fault that needs professional diagnosis.
• Verify furnace switch: Ensure the furnace service switch (often looks like a light switch near the unit) is in the ON position.
• Inspect junction box: Remove the cover on the furnace electrical box and check for loose wire nuts or burned connections. Tighten or replace as needed with power off.
• Check door interlock switch: Many Coleman furnaces have a door switch that cuts power when the blower door is removed. Ensure the door is properly installed and engaging the switch.

If power is present at the furnace but the LED remains off, the transformer or control board may be failed and should be tested by a technician.