How to Clean Your AC Filter

Cleaning your AC filter correctly can make the difference between breathing fresh air and circulating pet dander, mold, and dust. You’re likely familiar with the basics: turning off your AC system completely, carefully removing the filter, and rinsing it thoroughly under lukewarm water.

Yet, missing minor steps like vacuuming loose debris first turns cleaning into a messy chore, creating unwanted sludge that’s tougher to remove.

Done right, the cleaning process usually takes 15 to 30 minutes, though letting it fully dry can add several extra hours before reinstalling it safely.

In this article, I’ll also share expert insights from an HVAC professional to guide you through the process.

Difficulty: Easy Estimated Cleaning Time: 15 to 30 minutes Estimated Drying Time: 12 to 24 hours

Supplies Needed

Here’s what you need:

• Phillips and flathead screwdrivers (as needed for removing secured grilles or panels)
• Bucket (optional for soapy or vinegar solution)
• Mild dish soap
• Vacuum cleaner with brush attachment
• Soft-bristle brush (old toothbrush works great)
• Mild dish soap or vinegar
• Garden hose or a large sink
• Rubber gloves (optional but recommended)
• Face mask (optional, for heavy dust)

Step 1: Turn Off the AC System

HVAC expert Philip Crutchfield from Varsity Zone always tells homeowners to shut down their unit before starting any filter work. “Seriously—always start here,” he says, putting safety first.

Turn off the power at both the thermostat and the circuit breaker box. 

When you run your AC without a filter, even for a few minutes, dust, pollen, and other debris can enter the system and quickly build up on the coils and fans. This increases wear and reduces efficiency, making your cleaning efforts pointless. 

Plus, you don’t want moving parts suddenly starting up while your hands are inside the unit. Safety comes first, always.

Step 2: Locate and Remove the Filter

Removing your AC filter isn’t difficult once you know exactly where to look. Before pulling your filter out, quickly note which way it’s facing (most filters show airflow direction with an arrow) or take a photo to make reinstalling easier.

Crutchfield recommends handling the filter gently and not shaking it to avoid releasing dust into the air.

Remember, filter locations vary depending on your cooling system type:

• Wall-mounted Units: Most wall or split-type HVAC systems have filters behind their front panel. Tabs on both sides let you open this cover. Wear protective gloves if the area seems very dusty.
• Ducted Systems: The filter sits behind a rectangular air grille (often in your hallway ceiling). Some grilles pop open easily by pressing side clips inward, while others need loosening screws with a Phillips or flathead screwdriver before gently pulling them free.
• Window Units: Remove the unit’s front cover using either your hands alone (pop-off covers) or a screwdriver for secured ones. Behind that faceplate is the filter—usually it slides right out of place without effort.
• Portable ACs: Look on the side or rear panels; tabs commonly release filters outward without screws. You might need a Phillips head handy for secured panels that don’t slide free by hand.

*Note: If unsure, check your AC user manual—forcing covers or panels can accidentally crack or damage the filter.

Step 3: Inspect the Filter

Before you start cleaning, look at what you’re working with. If the filter is torn, bent out of shape, or falling apart, don’t bother cleaning it—just change it. 

A dirty but intact filter will look grayish or brownish instead of white or light gray. You might see visible clumps of dust, pet hair, or other debris stuck in the mesh.

Here’s a simple test: hold the filter up to a light. If you can barely see light coming through, it’s definitely time to clean it. 

*Note: Crutchfield warns that a common mistake is assuming all filters are washable. For more details, check our article: Washable vs. Disposable HVAC Filters: Which Are Better?

Step 4: Vacuum the Filter

Crutchfield strongly suggests vacuuming before washing your filter. He explains, “Vacuuming knocks off the loose dust, pet hair, and debris before water turns it into sludge. I’ve cleaned dozens over the years, and skipping this step just makes everything harder.”

Use a handheld vacuum or hose attachment with a soft brush. “I like the kind with gentle bristles,” Crutchfield says, “it’s effective but won’t damage the mesh.”

Lightly sweep carefully across both sides. For very dirty filters, wear gloves and a mask for extra protection.

Step 5: Wash the Filter

After vacuuming off edges and loose debris, you’re ready to wash your AC filter. 

Crutchfield recommends rinsing carefully with lukewarm (not hot) water from a sink faucet or garden hose on a gentle flow setting. Spray only from the clean side outward (the side facing away from inside your home), pushing dirt off the filter rather than pushing grime deeper into it.

For filters that are extra grimy, follow this simple five-minute cleaning guide:

• Fill a bucket with warm water and add a couple of drops of mild dish soap. For odor control, you can use a mixture of equal parts water and white vinegar instead. Never use harsh chemicals like bleach.
• Gently agitate the filter in the soapy water for 1 to 2 minutes, then let it soak for 5 to 10 minutes.
• If stubborn areas remain, use a soft-bristle brush to scrub the area lightly.
• Rinse again under slow-running, lukewarm water. Continue till absolutely clear of all bubbles and dirt residue.

Step 6: Let Your AC Filter Dry Completely

Always allow the filter enough time to fully air-dry before reinstalling it. Reinstalling a damp filter encourages mold growth and odors. Crutchfield suggests laying it flat in a dry, well-ventilated area.

You can place it outdoors in indirect sunlight or prop it vertically indoors. Don’t lean anything heavy on the mesh or frame, as it might warp out of shape. Dry time typically ranges from 12 to 24 hours, depending on your home’s humidity and airflow.

Warning: Avoid using high heat, like hair dryers or putting it in the oven. The heat can warp plastic components or damage the filter material.

Step 7: Reinstall the Filter

Once your filter is completely dry, reinstall it carefully into the AC unit or grille. If you forgot to check airflow direction earlier, look closely now—the arrow printed on the frame should point toward the system’s air handler blower and away from the return grille for correct airflow.

According to Crutchfield, your clean filter should sit neatly and firmly in position without any warped corners sticking out. If it no longer sits flush after cleaning or drying, then it’s probably worn out and needs to be replaced.

After positioning your confirmed-clean-and-solid filter correctly into its brackets:

• Put covers, grilles, and clamps (whichever you removed earlier) back securely.
• Restore power from the circuit breaker.
• Run a quick test cycle by setting your AC to “Fan Only” mode for 1 to 2 minutes first, then switch to cooling. Confirm smooth startup with improved airflow.

FAQ About Cleaning Your AC Filter

Clean Filters, Better Air, Fewer Repairs

Keeping your AC filter clean helps your home stay comfortable, improves indoor air quality, and prevents costly AC repairs.

Make HVAC maintenance a habit, especially during hot and cold seasons when your system does most of its work. Pay attention to signs like dusty smells or weaker airflow after cleaning, these hint that it’s time for a new filter. 

As HVAC pro Philip Crutchfield points out: “Reusable doesn’t mean forever.” Expect to change washable filters every 5 to 10 years, depending on how much your system runs and how regularly they’re maintained.

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Read More:

• What Causes an AC to Freeze Up?
• Why Is Your Air Conditioner Making Noise?

Main Photo: Cleaning the air conditioner filter in the bathroom AC unit. poko42 / Adobe Stock