How to Change Your Furnace / AC Air Filter

Regularly changing your furnace or AC air filter is one of the easiest ways to keep your HVAC system running efficiently and your indoor air clean. Most filters should be replaced every 1 to 3 months, depending on the type of filter, system usage, and indoor air quality conditions.

Step-by-Step: Changing Your Air Filter

1. Turn off your HVAC system
   For safety and to avoid drawing unfiltered air into the system, switch off the furnace or AC at the thermostat.
2. Locate the air filter
   Air filters are typically found in one of two places:
   • Inside the return air grille (on a wall or ceiling)
   • Inside or next to the furnace or air handler unit (often behind a removable panel)
3. Remove the old filter
   Slide out the existing filter carefully, noting the airflow direction arrow printed on the frame. You’ll want to match this direction when installing the new filter.
4. Check the size
   The filter size is usually printed on the frame (e.g., 16x25x1). Make sure your replacement filter matches these dimensions exactly.
5. Insert the new filter
   Slide the new filter into place with the airflow arrow pointing in the same direction as the old one—usually toward the blower motor or ductwork.
6. Secure the filter and turn the system back on
   Replace any covers or panels, then turn your HVAC system back on. You're done!