Kelvinator furnace shows E10 and will not start; control board LED may be off

Safety first: Use caution when working around 120 VAC. Turn OFF the breaker before opening junction boxes.

• Check breaker: Locate the furnace circuit breaker in the electrical panel. If tripped, reset once. If it trips again, there may be a short that requires professional diagnosis.
• Inspect service switch: Verify the furnace service switch (often mounted on or near the furnace) is in the ON position. Check for loose wire nuts or burned connections in the switch box (power OFF first).
• Door switch: Ensure the blower door is fully closed and depressing the door switch. A misaligned door can cut power to the control board.
• Control board fuse: With power OFF, inspect the board's line fuse if present. Replace only with the same type and rating. If it blows again, stop and call a technician.