How to Install an AC Filter

Co-authored by Victor Belavus

Last Updated: July 7, 2020 References

The filter for your AC unit helps keep the air in your home clean. It's important to change the filter regularly, as it collects dust, debris, and hair from pets and humans while pulling in air. A typical filter will be in a duct near the thermostat, though in a few cases, you may need to search a bit to find your filter.

Part 1

Part 1 of 3:

Changing a Typical Ceiling or Wall Filter

1
Purchase a new filter. You can find air filters at home improvement stores and most big box stores. If you're not sure what to buy, look at the size you already have after you pull it out. Basic air filters take care of things like dust and dirt. You can also buy filters to help reduce allergies, as they filter out more particles. However, the more they filter out, the less efficient they are because AC has to work harder to get the air through the filter.^{[1]
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Expert Source

Victor Belavus
Air Conditioning Specialist
Expert Interview. 6 May 2020.}
2
Look for the return air duct. Usually, the return air is located near your thermostat, either on the same wall or nearby. It's often near the floor on the wall and looks like a vent/grate.^{[2]
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Research source} However, it may also be in the floor, ceiling, the furnace, or even the air conditioner.^{[3]
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U.S. Department of Energy
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3
Pull open the return cover. Find the fasteners to pull open your grill work. Often, you'll have little fasteners that pull out and allow you to open one side of the cover. Lean the cover out towards you.^{[4]
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4
Remove the old filter. Take the old filter out, being careful of the dust. Most filters will have a buildup of dust that will shake off everywhere if you're not careful. Place the filter in the trash.^{[5]
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5
Place the new filter in the vent. Check for the airflow arrow on the vent. The arrow should point inward towards the duct not outward towards the grill. It should set right into the frame of the vent, as long as you have the right size.^{[6]
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6
Clean the grill. Wipe down the grill with a damp rag to remove buildup of dust and hair. You can also use a vacuum cleaner if it's particularly dirty. Run the hose along the vent on the outside and inside to clean it.^{[7]
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Part 2

Part 2 of 3:

Working with Odd Filters

1
Check inside your AC unit. With some units, especially indoor units, your filter may be inside the unit. Find the AC closet. Pull off the front panels. They should just slide off. Often, the air filter is at the bottom.^{[8]
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- Before pulling the filter out, check which direction the air flow arrow is pointed so you can install it correctly.
2
Look for a filtration system inside. Sometimes, you'll have a filter on the inside of the wall when your AC is outside. Often, the filter will just slide into a metal duct. You don't even need to open a grate.^{[9]
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3
Wipe off a reusable filter. Some ACs, particularly ductless filters, have a reusable filter. Switch the unit off, then remove the cover that houses the filter. Pull the filter out and wipe it clean before replacing it.^{[10]
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Part 3

Part 3 of 3:

Remembering to Change Your Filters

1
Write the date on the new air filter. Take the new air filter out of its package. It's helpful to write the date on the edge of the filter in permanent marker. That way, you know when you changed it last.
2
Change the filter at least every 3 months. Filters should be changed often, at least 4 times a year. However, if you live in a particularly dusty area, change it more often. You'll also need to change it more if you have pets.^{[11]
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Expert Source

Victor Belavus
Air Conditioning Specialist
Expert Interview. 6 May 2020.}
3
Set a reminder. If you have trouble remembering to change your filter, try setting a reminder on your phone or computer calendar. You can also write it on a wall calendar three months from the day you change it.

Expert Q&A
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Question

Can I fix a broken AC myself?

Victor Belavus
Air Conditioning Specialist
Victor Belavus is an Air Conditioning Specialist and the Owner of 212 HVAC, an air condition repair and installation company based in Brooklyn, New York. In addition to HVAC and air conditioning units, Victor also specializes in furnace repair and air duct cleaning. He has over 10 years of experience working with HVAC systems.

Victor Belavus

Air Conditioning Specialist

Expert Answer

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Outside of replacing the filter, it's typically not recommended for anyone outside of a trained professional to work on an AC unit. Just hire a professional to make sure the repair is done right.