Do Outdoor AC Units Have Filters?

Central and outdoor air conditioning systems rely on filters to circulate fresh, clean air throughout the home. Clogged filters can cause the unit to work harder.


, central air conditioners have a filter. In fact, most central air conditioning units have two or more filters.

These filters clean the air and ensure good air quality as the unit circulates between indoor and outdoor air. In some systems, the filters are located in the return air duct. This is the one that sends air from your space back to the air conditioner's air treatment system. If you have a large system with multiple air controllers and return ducts, finding the filters can be a challenge.

The air controller is a large metal box that houses the fan and the air conditioner motor. You can usually find it in the attic or basement. All central heating and cooling systems must have an air filter, but it may be more difficult to locate it in some HVAC units than others. The photograph shows a vertical or upward flow heating and air conditioning unit whose cooling section was mounted as a complement to a hot air oven.

The good news is that replacing your air conditioner filter is a simple task once you know how to find it. These systems move air from a return chamber (connected to the end of the system's return duct) through a cooling coil (for air conditioning) or a heat exchanger (for heating systems). When these problems occur in your home, you'll need a professional to diagnose and restore the unit's lifespan. In this photo of a slot intended to receive an air conditioning filter in the ventilation unit, the filter had simply been left out and the slot had been left open, drawing dirt, dirt, moisture and mold from nearby basement areas.

Horizontal air handlers, such as the horizontal air controller mounted in the attic pictured above, will cause return air to enter one end of the air handling unit and supply air that exits from the other end. The air filter prevents debris, dirt and other particles from entering the air conditioner unit, which can restrict airflow or contaminate the air. This photo shows an air filter located between a return air chamber (pictured on the right side) and the bottom of the air handling unit. When you reinsert the filter into the housing, make sure that the arrow points in the opposite direction of the return and is directed toward the air controller. When an air conditioner becomes clogged, not only does it not generate or circulate cold air inside the house, but it also compromises indoor air quality.

We'll replace the air filter on your air conditioner, clean the ducts, fix any other air conditioning problems you have, and answer all your questions. For the Ruud Achiever, super-quiet, 80-foot air controller, there is a molded permanent air filter that slides down to the back of the unit when you look at it from the burner side. Other vertical air handlers can be a downflow unit that has return air that enters through the top of the air handler or blower and air conditioner that exits to the supply ducts connected at the bottom of the unit.