Furnace blower runs but there is a strong burning or electrical smell from the vents.

Immediate safety: Turn off power at the breaker and service switch. Do not continue to run the furnace if you smell burning plastic or electrical insulation.

Steps:

• Remove the blower compartment door and visually inspect the blower motor and wiring for discoloration, melted insulation, or smoke residue.
• Spin the blower wheel by hand; if stiff or noisy, the motor bearings may be failing and the motor should be replaced.
• Check all wire connections at the IFC and junction box for tightness and signs of arcing (blackened or pitted terminals).
• Remove any debris from the blower housing.
• If the smell persists after cleaning and inspection, have a technician test motor amp draw and replace the motor or board as needed.