Burning or electrical smell from the unit during operation.

Safety first: Immediately turn off and unplug the unit if you smell burning plastic or insulation. Do not continue to operate until inspected.

Steps:

• 1. Initial burn-off: If the unit is new or has not been used in heat mode for a long time, a brief burning-dust smell may be normal for the first 10–20 minutes. If it persists, investigate.
• 2. Visual inspection: With power disconnected, remove covers and inspect wiring, connectors, and the control board for discoloration, melting, or burn marks.
• 3. Check motors: Smell near the indoor and outdoor fan motors. A strong burnt odor may indicate a failing motor that should be replaced.
• 4. Heater element (if equipped): On electric heat models, inspect the heater element area for debris or signs of overheating.
• 5. Do not ignore: Any ongoing burning smell requires immediate professional inspection and repair to prevent fire risk.