Do central air conditioners have filters? The answer is yes! Most central air conditioning units have two or more filters that clean the air and secure good air quality as the unit circulates between indoor and outdoor air. These filters reduce pollen, bacteria, dust, and pet dander, while also protecting the air conditioner coils and engine from contaminants. The air filter is usually located close to the home thermostat, in a return duct or next to the air controller in your air conditioning system. If your HVAC unit is installed in the attic, it may be installed in a ventilation grille instead.
It's important to find all the filters, as some systems have several filters and even different types of filters such as fiberglass, pleated paper, washable, and electrostatic air filters. If you can't find the air conditioning system filters, here are some places to look: inside the metal box that contains the fan, fan motor, condenser coil, and compressor; inside a place that will filter the air before it reaches the fan; and in return ducts or ventilation grilles. For those living in the country with less air pollution, there may be less need for filtration. Vertical air handlers can be an upflow unit that has return air entering through the bottom of the unit and cooled or heated air exiting from the top.
It's important to consider adding additional layers of filtration without talking to your HVAC company about the airflow rate requirements of your system and the restriction of additional filters to ensure that you are not slowing down the air supply through the system. If you have a new house and can't find a filter in your attic air conditioning unit or roof suction tubes, be sure to document the location of any HVAC system air filters for future building owners, occupants, or repairers.