Lennox air conditioner produces a musty or moldy smell when it starts, especially after being off for a while.

Safety: Turn off power to the indoor unit. Wear gloves and a mask when cleaning moldy components.

• 1. Inspect coil and pan: Remove access panel and look for slime, mold, or debris on the coil and in the pan.
• 2. Clean coil: Use a non-acidic foaming coil cleaner approved for indoor use. Follow label directions and rinse if required.
• 3. Disinfect drain pan: Clean the pan with a mild bleach solution (if compatible with materials) or an HVAC-approved biocide. Rinse thoroughly.
• 4. Improve filtration and humidity control: Install a quality Lennox filter and consider adding a Lennox whole-home dehumidifier if humidity is consistently high.

Note: Avoid using strong fragrances or unapproved chemicals inside the air handler; they can damage components and irritate occupants.