Furnace emits a burning smell when it starts, especially after long periods of inactivity

Safety: If you smell burning plastic or see smoke, turn off power immediately and do not use the furnace.

• Initial seasonal use: A mild burning dust smell for the first 10–30 minutes of operation after a long off period can be normal. Open windows to ventilate.
• Inspect interior: With power off and cooled, remove the access panel and vacuum dust from accessible surfaces, avoiding direct contact with sensitive electronics.
• Check wiring: Look for discolored or melted insulation on wires. If found, call a technician.