Furnace emits a burning smell or plastic odor when running.

Safety: If you see smoke or suspect an electrical fire, turn off power immediately and contact emergency services. Do not ignore persistent burning smells.

• Initial burn-off: A slight smell may be normal after first startup or after long inactivity as dust burns off. This should disappear after a few hours.
• Inspect visually: With power off, remove the front panel and look for discolored or melted wiring, especially near the fan, pump, and control board.
• Clean dust: Use a vacuum and soft brush to remove dust from accessible surfaces, avoiding direct contact with electronics.

Any sign of overheated wiring or components requires professional inspection and repair.