In most homes, central air conditioners work together with an existing forced-air system to cool and circulate air. The air is cooled when it passes over the central air conditioner's evaporator coil , which is the main component of the system located inside the house. The cooled air then travels through the ducts into the home while room-temperature air is pulled into the furnace's return air duct, beginning the cycle again.
The condeser unit , which is located outside the home, is the other main component of the central air conditioning system. Both the evaporator coil and condenser are sealed systems, and require servicing by a professional technician. However, homeowners can perform some basic air conditioner maintenance that can keep the system's components clean and functioning properly.
The evaporator is usually located above the furnace in the plenum. If the front of the plenum is covered by foil-wrapped insulation, you should be able to clean the evaporator - but if you're not comfortable cleaning the evaporator yourself, a professional technician can do this as part of your A/C system's annual maintenance.
Carefully remove the insulation from the front of the plenum, which may be taped in place. Ac access plate should be located behind the insulation - remove the screws securing it to the plenum to gain access to the evaporator.
The underside of the evaporator should be cleaned with a stiff brush. When the coils are free of dust and dirt, clean the tray below the evaporator, then replace the access panel and insulation. Periodically cleaning the evaporator allows heat to transfer easily from the air to the coils, and can help maximize the efficiency of the air conditioner.