Furnace emits a chemical or plastic smell during operation.

Safety: Turn off power if the smell is strong or accompanied by smoke.

• Check surroundings: Ensure no plastic, paint cans, or chemicals are stored on or near the furnace or flue pipe.
• Inspect casing and flue: Look for melted plastic or scorch marks on the furnace body and venting.
• Ventilate area: Open windows to clear fumes.

If the smell persists without an obvious external cause, have a technician inspect internal wiring and components for overheating.