Heat pump air filters should be changed at least twice a year. Here is how to replace them. If you want a quick view on changing filters, see the video at the bottom of the page.

Air filters are an important part of a heat pump heating or cooling system. They remove dust and allergens before returning the cooled or heated air to your rooms.

Over time, however, they become clogged with dust and debris. When this happens, they block the free flow of air. This drastically reducing the system’s efficiency.

By properly maintaining filters, you can keep your system working as affordably as possible.


Replace disposable filters or clean permanent air filters at least once every six months—sooner if they become clogged with dust.

Filters may be located at the return-air registers in the home or in the heat pump’s air-handler cabinet. In many cases, they are in both places.

The first step is to turn off the heating or cooling system and then locate the filters and measure their sizes (or note the sizes marked on their frames).

To replace a filter located in a room’s return-air duct register:

The return-air duct is usually larger than the registers used for delivering heated or cooled air to rooms. It is typically located in the wall or ceiling at a central location such as a hallway. Many homes have more than one, so that air can be drawn from multiple locations.

1 Unlatch the return-air register’s cover grille and swing it out of the way or remove it. Take care to prevent its hinged side from unhooking—it will fall if this happens.

cleaning heating register
Clean dust off of filter grilles and registers, and change filters twice a year. Steve Heap / Shutterstock.com

2 Remove the old filter. It should just be resting on a ledge or channel. immediately slip it into a trash bag and put it in the outdoor trash. Use a damp rag or dust mop to remove dust from the grille and the surfaces of the register—both inside and out.

3 Then position the new replacement filter in the register with the airflow arrows pointed in toward the ductwork.

Position the replacement filter (in this case, located in a wall register) with airflow arrows pointing in toward the ductwork. ©Don Vandervort, HomeTips

4 Finally, replace the register’s grille and latch it.

To replace the filter in the air-handler cabinet:

1 Turn off the power to the unit.

reset circuit breaker
Turn the circuit breaker all of the way off, then flip it back to “ON.” © HomeTips

2 Remove the door or panel from the blower cabinet. Lift this door or panel off its holding hooks or unscrew its retaining screws to remove it.

service person doing forced air furnace care

3 Check the filter. A standard filter is mounted next to or under the blower motor. Slide the filter out along its tracks.

furnace forced air heating
Furnace Parts Diagram

Check to see whether it is a disposable filter or intended to be cleaned and replaced—this should be marked on the filter’s edge, along with directions for cleaning, if applicable. If it’s a disposable filter, its size will more than likely be printed on the frame’s edge.

4 Buy a replacement filter and slide it back into place, noting the arrows stamped on the side that indicate the proper direction of airflow; be sure you face these toward the blower (away from the ductwork). Then replace the door to the cabinet.

Mark the date on the filter's frame so you'll know when it's time to change it. Note: Be sure the "air flow" arrow is pointing in the right direction.
Mark the date on the filter’s frame so you’ll know when it’s time to change it. Note: Be sure the “air flow” arrow is pointing in toward the blower. ©Don Vandervort, HomeTips

Check out this video by Don for a quick view of changing furnace or heat pump filters:

Changing a furnace filter video shows how
Don Vandervort, HomeTips © 1997 to 2023 | HomeTips

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About Don Vandervort
Don Vandervort has developed his expertise for more than 30 years as a remodeler and builder, Building Editor for Sunset Books, Senior Editor at Home Magazine, author of more than 30 home improvement books, and writer of countless magazine articles. He appeared for 3 seasons on HGTV’s “The Fix,” and served as MSN’s home expert for several years. Don founded HomeTips in 1996. Read more about Don Vandervort