How to Clean an AC Filter

Air conditioning units don’t require a lot of maintenance, but it's important to clean or replace your unit’s air filters regularly to reduce the likelihood of airborne mold and common allergens through forced air systems. There are different types of air filters available, and though many are disposable and can’t be cleaned, thanks to changes in technology and related efficiencies, washable air filters are more common than ever. If you’ve previously used disposable filters, this might even be the perfect time to upgrade.

Why Should You Clean Your Air Filter?

• Cleaner air quality: fewer allergens and less dust.
• Better unit efficiency, which results in lower energy costs: Dirty filters make the system work harder. The harder it works, the less efficient it is. The less efficient it is, the more it costs to operate.
• To prolong the life of your HVAC unit: This is tied to efficiency. The harder the system works, the faster it can be damaged or overheated.

Types of AC Filters

Disposable Filters

These are usually made of paper or cardboard and cannot be cleaned; they should be thrown away and replaced. You may buy these in bulk to make it easier to replace several times a year, but if you’re running low on replacements and are considering alternatives, this may be the time to invest in washable filters.

Washable/Reusable/Permanent Filters (aka Electrostatic Filters)

These are considered permanent since they can be cleaned and reused for years; some electrostatic filters are designed to last for the life of the HVAC system with proper care. Reusable filters are more expensive upfront but can save you money in the long run. They’re typically less effective at capturing small particles than disposable filters, so they may not be the best choice if you or anyone in your household has allergies.

• Most use air friction to create electrostatic cling to trap particles. You’ve experienced static cling, and this is no different.
• If you’re replacing a disposable filter with a reusable filter, make sure to get the highest MERV filter rating (Minimum Efficiency Reporting Value) your system allows.

It’s always a good idea to save the packaging or take a photo of it when you replace your filter because knowing exactly what type of product you purchased is the first step to knowing if and how it can be cleaned. Also, make it a habit of marking on your calendar when it needs to be cleaned or replaced so you can easily remember.

Once you know what type of filter you have and understand its expected lifespan, you can get to cleaning.

How to Clean an Air Filter

1. Turn Off the AC Unit

Keeping the unit off ensures that you’re not letting dirty air circulate through your home while the filter is being cleaned.

2. Remove the Filter

Some units can have multiple filters, so be sure you check all vents.

3. Vacuum the Filter

To reduce the amount of dust buildup, the first thing you can do is use a hand vacuum to lift allergens. Use the microfiber cloth to clean any dust along the frame. Getting this top layer of sediment and anything loose makes the next step clean and easy.

4. Wash the Filter

In a deep sink or outdoors using a garden hose, rinse the filter gently and thoroughly, and allow it to dry. If you need to provide a deep clean, soak the filter in a flat bin with 1 part white vinegar and 1 part warm water for an hour, and then rinse it gently with the hose.

Never use a pressurized cleaner on an air filter; they’re simply too delicate for any high-pressure hose.

5. Reinstall the Filter

Check the dry filter for any signs of damage — holes, dirt that could not be cleaned thoroughly or rips in the material. If it's in good condition, you can put it back in the unit. Refer to any expiration dates on the product or its original packaging to make a note of when it needs to be fully replaced.

Other Filters on an AC Unit That You Can Clean

The fins of a window AC unit can be vacuumed or wiped down with a microfiber cloth to remove dust and debris for greater efficiency. Be careful not to bend or squish the fins together. The fins are how the A/C unit “conditions” the air.

• Unplug the unit.
• Vacuum or gently brush in the same direction as the fins.
• Use a butter knife to gently straighten bent fins if necessary.

The exterior of an outdoor central AC unit can be cleaned as well.

• Remove large debris by hand (leaves, grass clippings or anything else that has been collected by the unit).
• Use a garden hose to wash smaller debris off of the unit.
• Use a butter knife to gently straighten bent fins if necessary.