Lennox air conditioner runs but does not cool well; the supply air is only slightly cooler than room temperature.

Safety: Turn off power before cleaning coils or opening panels.

• 1. Check filter and airflow: Replace dirty filters and ensure vents are open. Poor airflow reduces cooling capacity.
• 2. Clean outdoor coil: Remove debris and wash the Lennox condenser coil from inside out with a hose.
• 3. Inspect indoor coil: If accessible, check for dust buildup and clean carefully with coil cleaner.
• 4. Check for duct leaks: Inspect accessible ducts in the attic or basement for disconnected joints or large leaks and seal with mastic or UL-181 foil tape.

Note: If performance is still poor, a technician must check refrigerant charge and system sizing.