Air conditioner runs but does not cool the room effectively; supply air feels only slightly cooler than room air.

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

Steps:

• Clean filters: Remove and wash the indoor air filters thoroughly.
• Clean coils: Inspect and clean both the indoor evaporator coil and outdoor condenser coil using appropriate coil cleaner.
• Check fan speeds and mode: Ensure the unit is set to COOL mode with an appropriate temperature setpoint and medium/high fan speed.
• Seal room: Close windows and doors; reduce heat loads from direct sun and appliances.

If performance remains poor: A technician should check refrigerant charge, verify correct installation of the refrigerant line set, and confirm the system is properly sized for the space.