Furnace will not start at all; no inducer, no blower, no LED lights on York control board.

Safety: You are dealing with 120V power. If unsure, call a professional.

• Check breaker: At the electrical panel, locate the furnace breaker and ensure it is ON. If tripped, reset once. If it trips again, stop and call a technician.
• Furnace switch: Verify the furnace service switch (often looks like a light switch near the unit) is ON.
• Door switch: Remove and reseat the blower door to ensure the door safety switch is fully depressed when closed.
• Inspect junction box: With power off at the breaker, open the furnace junction box and check wire nuts for loose connections or burnt wires.
• Transformer check: If the LED is off but 120V is present at the board, the 24V transformer may be failed. This should be tested and replaced by a technician using a multimeter.