How to Change Your Heat Pump's Air Filter

By Missy Nolan

February 09, 2026

If a dirty heat pump filter could talk, it would probably ask to borrow your inhaler. Think of your heat pump's air filter as the lungs of your HVAC system. The filter pulls in air, capturing dust and debris, so your heating and cooling system can breathe easier. Protect indoor air quality and the lifespan of your HVAC system by learning how to change heat pump filters.

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Keep reading to find out more about the role of a heat pump filter. We'll also walk you through heat pump filter replacement step by step and share some common dirty filter signs.

What Is an Air Filter on a Heat Pump?

Your heat pump's air filter stops dust, pet hair, pollen and other airborne pollutants from entering your HVAC system. These tiny particles can make your family cough, wheeze or sneeze, especially if loved ones have asthma or allergies.

Airborne pollutants also affect your HVAC system's performance. A clogged filter doesn't promote healthy airflow, which means your system works harder than necessary. Unlike air conditioners and furnaces, your heat pump handles heating and cooling. That means your system runs year-round, hopefully with a clean filter.

Where Is My Heat Pump's Air Filter?

The location of your HVAC air filters depends on the type of system you have. You might find the filter on the bottom or side of your unit when you go to change a heat pump filter. Your filter might also be hiding in a cabinet or behind a large air vent.

Here are some tips on finding HVAC air filters based on the type of system you have:

1) Air Handler Filter Location

Some heat pump components are found outside, but your air handler is typically inside. An air handler is part of your heat pump. It moves conditioned air through your home's vents, keeping your interior warm or cool.

You can find air handlers in closets, attics, basements and garages. An air handler filter usually slides into the side or bottom of your system.

2) Return Vent Filter Location

A return vent grabs indoor air, pulling it back into your HVAC system. This air gets filtered and reconditioned before being sent back into your home. You can often find return vent filters in walls, floors or ceilings. Look for a large return air vent, then gently pop it loose to locate the air filter.

3) Furnace or Hybrid Systems

Homeowners with a dual fuel setup should check the furnace cabinet during heat pump filter replacement. Your cabinet should house the furnace and be inside of the home.

Need extra help locating your HVAC air filters? Check your owner's manual or contact an HVAC tech for assistance.

How to Change a Heat Pump Filter

Put your toolbox away. You'll need few, if any, tools when you change a heat pump filter.

You may find it helpful to have these tools and materials available:

A new air filter (make sure it matches the measurements of your current filter)
A flashlight or other nonflammable light source
A screwdriver if any components are secured to a wall or ceiling
A vacuum and/or rag for cleanup (you might notice a lot of dust)
The owner's manual for your heat pump, if available

After gathering your supplies, it's time to change the heat pump filter. Every system is different, but here are some general step-by-step instructions for homeowners:

1) Turn Off Your HVAC System

Safety first! Turn off your HVAC system by locating the thermostat. Make sure the thermostat says Off, not On, Fan or Auto. Otherwise, unfiltered air can get sucked into your system during the heat pump filter replacement.

2) Locate the Filter Slot

Look for the air handler or return vent, then find the grille or access panel. As we mentioned earlier, filter slots may be on the side or the bottom of the system. Filter slots may be in closets, cabinets, ceilings, walls or floors. Check the basement or garage if you don't see your HVAC system in another part of your home.

3) Open the Filter Slot

You can typically open the filter slot without tools by popping it out with your fingers. There may be a latch for easy opening. You may need a screwdriver if the filter slot is secured tightly.

4) Remove the Current Air Filter

Slowly and carefully slide out the existing air filter for your heat pump. Set the filter aside or dispose of it immediately.

5) Verify Size and Airflow Direction

Compare the numbers on your old air filter with the new one. You may see measurements such as 16x20x1, for example. The numbers should match.

After checking these numbers, make sure your airflow direction is correct. The arrows should point toward your air handler, not the room. Some filters may also say "this side up" or something similar.

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6) Install the New Filter

Carefully slide your new air filter into the designated slot. Do not force the air filter into the slot. It should be snug but not overly tight.

7) Close the Filter Slot and Panel

Close the filter slot along with any other open components, such as vents, panels or grilles.

8) Turn on Your HVAC System

Power your HVAC system back on and enjoy breathing clean, filtered air!

How Often Should You Replace Heat Pump Filters?

Some homeowners replace filters quarterly, while others do monthly or bimonthly swaps. Your filter replacement schedule depends on the following factors:

How often you cook meals at home (and whether those meals push particles into the air)
Whether you have pets
The thickness and type of your air filters
The size of your home

An HVAC professional can help you determine the perfect replacement schedule for your home.

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