How to Replace Air Conditioner Filters
Locate and Open Air Filter Cabinet
When it’s time to inspect your filter, always be sure to turn off power to the system. You can do this either at the thermostat, the breaker box, or using the shutoff switch located on/near the indoor unit (often looks like a light switch).
The exact location of the filter can vary depending on the indoor HVAC unit and type of system. Most single-home residential systems include either a vertical or horizontal indoor air handler unit (furnace or fan coil), typically in a basement, furnace/utility closet, garage or sometimes an attic. Look for a filter cabinet along the sides, top or bottom of the blower cabinet. The filter may be positioned horizontally or vertically, depending on the orientation of the air handler in the indoor unit. In some cases, especially on older models, the filter may be found inside the blower cabinet. If you live in a multifamily apartment or condo unit, the filter may be located in an in-wall return air grill.
Once you have ensured that power is shut off and located the filter, take a moment to determine the direction air flows through the system. Some filters will include air flow arrows to ensure proper installation. If arrows are present, take note of the direction they are pointing so you can properly re-install the old one or install the new one. Now, remove the filter from its housing and inspect it for excessive build-up of dust, dirt and debris.