Lennox air conditioner emits a burning or electrical smell when running.

Safety: If you smell burning plastic or see smoke, turn off power immediately at the breaker and do not operate the system.

• 1. Determine if smell is brief: A mild dusty smell at first use of the season may be normal as dust burns off.
• 2. Inspect blower and wiring: With power off, check the blower motor for discoloration, melted insulation, or burnt smell. Inspect wiring at the Lennox control board and contactor for signs of overheating.
• 3. Tighten electrical connections: Loose lugs at the contactor, disconnect, or breaker can overheat. Tighten with power off.
• 4. Do not ignore persistent odor: If the smell persists or worsens, have a technician inspect for failing motors, capacitors, or wiring.

Warning: Electrical overheating is a fire hazard; address immediately.