How to Check and Replace Your Central Air Unit Filter

You can easily tell if you need to clean or replace the air filter by taking it out of your camera and attaching it to the light. If light can easily pass through the filter and is semi-transparent, you can leave it on. However, if it is difficult for light to pass through and it is visibly dirty, you should replace the filter. The air filter is usually close to your home thermostat, in a return duct.

Or, it's most likely right next to the air controller in your air conditioning system. It's important to keep in mind that many air filters are directional: air is designed to flow through the filter in only one direction. Look for an arrow or airflow symbol that indicates the direction. The arrow should point to the oven or air controller.

If the filter doesn't have arrows, check if one side of the filter looks rougher than the other; that would be the side that collects dust, so the other side would be facing the equipment. Additionally, you may want filters that do more than just keep dust out of the air conditioner. If you want to improve air quality in your space by eliminating pollen, mold, and other harmful contaminants, you should invest in HEPA filters with a MERV rating of 10 or higher. Start by looking for a waste source near the central air return system; continue to look for leaks that could attract debris to the return air duct system anywhere along its length.

If, by any chance, you don't have a regular HVAC service technician asking you how to change an air conditioning filter, you've probably neglected other important maintenance tasks besides changing your air conditioning filters. Follow the path of the air, find the return air, which will tell us where a filter can be placed; there are more illustrations on the page above. To clean the air conditioner filter, make sure the unit is turned off before removing the filter. In addition, the system will have high operating costs because the air flow is unidirectional and constantly draws new air from the basement to the air handler to heat or cool it and send it only one way to the living room. Every month during the heating or cooling season, inspect the type and condition of your air conditioner filter.

Knowing where air filters are normally located can help you find dirty or clogged filters that increase air conditioning or heating costs. Provide information about where these filters are located: MORE examples of where and how to look for filters in an air conditioning or hot air heating system. The photo at the top of this page shows another conventional air filter located inside the vertical fan compartment of the air handler; in that case, the filter was very dirty and clogged by dirt. 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 exits to supply ducts connected at the bottom of the unit. Once you have located all of your filters, document their location for future building owners, occupants, or repairers.

Replacing your home's air conditioner filter will allow your unit to continue to blow cold air without interruption. When in doubt, it's best to ask your HVAC technician to provide you with correct filters or show you filter size information so you can order them yourself. I think that wire grille you showed above is intended to hold an air filter at the top of the return air chamber.