Concord furnace has no LED lights and does not respond; blower and inducer are off.

Safety: Before working on electrical components, turn off the breaker and verify power is off with a non-contact tester if available.

Steps:

• Check breaker: Locate the furnace circuit breaker in the electrical panel. If tripped, reset once. If it trips again, do not continue resetting; investigate further.
• Check service switch: Ensure the furnace service switch (often mounted on or near the furnace) is in the ON position.
• Inspect door switch: Remove and reinstall the blower door, ensuring it fully depresses the door safety switch. A misaligned door can cut power to the control board.
• Check board fuse: With power off, inspect the low-voltage automotive-style fuse (typically 3–5A) on the integrated furnace control. Replace if blown with the same rating. If it blows again, there is a short in the 24V circuit (often thermostat wiring or outdoor unit contactor coil).
• Inspect wiring connections: Verify that line voltage wires are secure at the furnace junction box and control board.

Call a professional: If fuses or breakers continue to trip, a short circuit or motor failure may exist and should be diagnosed by a technician.