Skip to main content

Replace Filter — Remove the Old Air Filter

Beginner15 mins

Part of project

AC Filter Replacement · Step 3 of 8

Helpful?

In this video

Once you've located the filter housing (in this case, in a hall closet near the floor), carefully slide out the old, dirty air filter. Before discarding it, take a moment to observe the small arrow printed on the filter's frame. This arrow indicates the direction of airflow, which is critical for proper installation. Retrieve your new HVAC filter (the video shows a standard pleated air filter). Align the new filter so that its airflow arrow points in the same direction as the old one (typically towards the furnace or air handler, or into the main HVAC unit). Gently slide the new filter into its designated slot until it is fully seated. Finally, close any access doors or covers that were opened to reach the filter housing.

74.2K views103

FAQs

How do I find the correct size and type of replacement filter?

The filter size is usually printed on the cardboard frame of your old filter (e.g., 20x25x1). Note down these dimensions before buying a new one, like the ACDelco Air Filter A2014C. For filter type, MERV ratings (Minimum Efficiency Reporting Value) indicate how effectively a filter cleans the air; consult your HVAC system's manual or a professional to choose the appropriate MERV rating for your system.

Can I clean my old AC filter instead of replacing it?

Most residential AC filters, especially disposable pleated or fiberglass types, are not designed to be cleaned and reused. Attempting to clean them can damage the filter media, reducing their effectiveness and potentially pushing debris into your HVAC system. Always replace disposable filters with new ones to maintain air quality and system health.

What are common mistakes people make when replacing an AC filter?

A common mistake is installing the new filter backward; always ensure the airflow arrow on the filter points in the direction of the furnace or air handler. Another error is forcing the wrong size filter into the slot, which can lead to air bypassing the filter and reducing efficiency. Always double-check the dimensions and the airflow direction arrow before installation.

What if I can't find the filter slot on my furnace or air handler?

The filter slot is usually located where the return air duct enters the furnace or air handler, often in a dedicated slot near the main unit. It might also be behind a return air vent grille in your ceiling or wall. If you're having trouble locating it, consult your HVAC system's manual or look for a hinged door or cover near the main unit where the large air duct connects.