The thermostat calls for heat, but the furnace inducer never starts; the LED is on and shows a normal or no-fault indication.

Safety first: Turn off power before touching the inducer or its wiring. Do not operate the furnace with the inducer disconnected.

• Listen for the inducer: When the thermostat calls for heat, you should hear the inducer motor start within a few seconds. If it remains silent, proceed with further checks.
• Check inducer wiring: With power off, inspect the inducer motor plug and wires for loose connections or burn marks.
• Spin test: Try to spin the inducer wheel by hand. It should move freely without grinding. A seized motor or wheel requires replacement.
• Voltage test (qualified persons only): With power on and a call for heat, measure the voltage at the inducer motor terminals. If the rated voltage is present but the motor does not run, the inducer assembly is faulty.

If no voltage is present at the inducer when there is a call for heat, the control board's inducer relay or the board itself may be faulty.