Musty or moldy odor from the air conditioner when it starts.

Safety: Unplug the unit. Use appropriate respiratory protection if you are sensitive to mold.

Steps:

• Clean filters: Wash or replace air filters.
• Clean evaporator coil: Spray a foaming coil cleaner approved for indoor use onto the evaporator fins. Allow it to work and drain as directed.
• Disinfect drain pan: Access the drain pan under the coil and clean it with a mixture of water and mild detergent or a coil-safe disinfectant. Ensure the drain hole is clear.
• Run fan-only mode: After cleaning, run the unit in fan-only mode for 30–60 minutes to help dry the coil and pan.