Indoor unit and outdoor unit both run but cooling is weak; supply air only slightly cooler than room

Safety first: Turn off power before cleaning coils or filters.

Steps to try:

• Clean indoor filters and coil: Wash filters and, if accessible, clean the evaporator coil with a coil-safe cleaner.
• Clean outdoor coil: Remove debris and rinse the coil fins gently.
• Check fan speeds and mode: Set fan to HIGH and mode to COOL. Ensure doors and windows are closed.
• Measure temperature drop: After 15–20 minutes of operation, measure air temperature at the return and supply. A typical drop is 15–20°F (8–11°C). Much less suggests a refrigerant or capacity issue.

When to call a pro: If cleaning and proper settings do not restore performance, a technician should check refrigerant charge and system sizing.