How to Clean Your Window AC Unit—and the Gross Things That Can Happen If You Don’t

It's hot. Like, really hot. Learn how to clean a window AC unit, and you can stay cool all summer long.

Millions of Americans are under heat warnings this summer, and window air conditioners are working overtime. You know how it is: You come home from a long, hot day, and all you want to do is bask in that sweet, cold blast. When the temps climb, nothing feels better. Learning how to clean a window AC unit is the last thing on your mind.

Well, we’ve got some good news and some bad news. The bad news? You have to clean your air conditioner. Air quality goes way down when you neglect your AC. Do you really want dirt, dust and molds blowing around your house? Plus, dirty ACs are inefficient and have trouble cooling, which in these temps is a disaster waiting to happen. You could be shelling out major bucks when your struggling AC conks out.

So, what’s the good news? Learning how to clean a window AC unit is a breeze! (Sorry.) Seriously, it’s not hard at all, and when the temperature’s pushing 100, the last thing you want to be without is air conditioning. If you’re ready to put your window air conditioner on the cleaning schedule, we’ve got expert tips to keep you from making major air-conditioning mistakes that can shorten the life of your air conditioner. Your lungs will thank you too!

Get Reader’s Digest’s Read Up newsletter for more cleaning, humor, travel, tech and fun facts all week long.

What happens if you don’t clean your window AC unit?

Mold Inside The Air Conditioner.Symfonia/Getty Images

Did you know the average person spends 90% of their time indoors? Michael Rubino, author and air-quality expert, says due to today’s building efficiency standards, we don’t get a lot of fresh air interchange either. And contrary to popular belief, most window air conditioners don’t bring in fresh air from outside. That means that if you’ve got dust and mold spores in your house (and who doesn’t), that junk just recirculates throughout your home if you don’t keep your AC and filter clean.

Rubino says appliances, including window air conditioners, are havens for mold activity, thanks to the abundance of moisture and the food in the form of dirt and dust. Keeping your window air conditioner clean and dry can help reduce the presence of these airborne contaminants.

Both your wallet and your air-conditioner unit will benefit from regular cleanings too. “Not properly maintaining the window AC unit can cause it to work harder to cool the space, increasing [your] energy bill,” says Brad Roberson, president of Aire Serv Heating & Air Conditioning. “And [it] could shorten the life of the unit.”

How often to clean your window AC

How often you need to clean your air conditioner depends on the part you’re cleaning, according to Glory Dolphin Hammes, CEO of IQAir North America. Air conditioners have coils and filters, and both parts need to be cleaned. “The filter needs to be cleaned once a month,” according to Hammes. “The coil should be cleaned annually.”

Start by cleaning it when you take it out of storage, says Roberson. Your window air conditioner sits all winter in a dusty old garage, perhaps even in the window, collecting dust and potentially leaves, mold, animal hair and other debris. Spring cleaning offers the perfect opportunity to tackle the coil and the rest of the interior with a good old deep-clean.

Then, throughout the season, clean the filter and wipe down the exterior. Your AC will thank you.

How to clean a window AC unit

Air conditioner cooling coil that half comparison between thick dust and cleanTanut Nitkumhan/Getty Images

By this time in the season, your AC is probably due for a cleaning. Depending on your level of grime, we’ve got three options for you.

Maybe you stuck it in the window in May and haven’t looked at it once. In that case, it’s probably time for a deep-clean, even if Roberson recommends tackling that task before the season starts. But if you’re just looking for a quick clean and filter scrub, we’ve got you covered too.

How to do a quick cleaning

Even if you started with a clean air conditioner earlier in the spring, dust and dirt build up, causing your unit to run less efficiently. A quick cleaning of the front panel will help, and when you combine this step with filter cleaning, your AC will blast cold air all summer long.

Ready to learn how to clean a window AC unit in a flash? Keep reading.

Gather your supplies:

Step 1: Open the front and remove the filter

A Woman Holding A Dirty And Dusty Air Conditioner Filter to clean the filterBomberMoon/Getty Images

Open the front panel door. It may be attached by screws, but it likely just pops open for easy cleaning.

Locate the filter and remove it. Most window units have washable filters that just slide right out, but it’s worth checking your manual. In this heat, the last thing you want to do is break something!

Step 2: Clean the front panel

Hand In Yellow Glove And Vacuum Cleaner Pipe cleaning ventilation vents for home air conditioningPaulBieyukov/Getty Images

Start by vacuuming the front panel to remove dust bunnies and loose dirt or dust. Work the brush into the crevices from both sides. For mildly dirty slats, load up your microfiber cloth with warm, soapy water, and wring well. Wipe down the front grille, working the microfiber cloth into the slats to remove grime the vacuum didn’t pick up.

If your front panel is really dirty, remove it entirely and scrub it in the sink. (Then clean your sink so it sparkles.)

Step 3: Clean the filter

Follow the steps below to clean and replace your air-conditioner filter.

How to clean an AC filter

Man Holding Very Dirty Air Conditioner Filter against the light to spot dust and debris in the filterTriocean/Getty Images

Your air conditioner’s filter is your main defense against dust, dirt, molds and every other gross thing that’s floating around in the air, so even if you don’t feel like cleaning your entire window air conditioner, don’t neglect the filter. Hammes suggests cleaning it monthly, while Roberson prefers checking and cleaning your filter every few days during times of heavy use. Don’t worry, this step’s a snap.

If your air conditioner has disposable filters, washing isn’t necessary. But Roberson recommends replacing them every three months (just like your water filter).

Gather your supplies:

  • Vacuum with brush attachment
  • Soft brush or cloth
  • Dish soap
  • Garden hose or sink spray nozzle

Step 1: Remove and clean the filter

Clean The Air Conditioner Filter With Fresh Water to remove dirt dust and debris from filter screenBomberMoon/Getty Images

Check your manual for instructions on how to remove the filter for cleaning. It may be contained within the front panel or resting right behind it. If the filter is washable, remove it and vacuum using your attachment brush.

Next, soak or spray the filter with warm, soapy water and rinse well. For filters that are reusable but not washable, simply vacuum and replace them.

Step 2: Dry and reassemble

Allow your washable filter to dry thoroughly, then slide it back into the air conditioner.

How to deep-clean a window AC unit

Luckily, you have to deep-clean your unit only once a year. Hammes says it’s easy but requires some elbow grease, so gather your supplies and roll up your sleeves.

If you’re still learning the basics of how to clean a window AC unit, follow Roberson’s advice: The beginning of the season, when you drag your air conditioner out of storage, is the perfect time to do a deep-clean. Whenever you decide to tackle this task, make sure the unit is unplugged before you start!

Gather your supplies:

  • Vacuum with brush attachment
  • Phillips screwdriver
  • Spray bottle
  • Dish soap
  • Distilled water
  • Towel or microfiber cloth
  • Soft cleaning brush
  • Credit card, butter knife or other thin, dull tool

Step 1: Remove and clean the front panel and filter

Aluminum Air Conditioner, Condenser Coils Dirty And DustyMariusLtu/Getty Images

Remove the front panel to access the filter and evaporator coils. You may need a screwdriver, or it could just snap off. Remove the filter by either sliding it out from inside the panel or just lifting it out (check your manual).

Wipe down the grille with warm, soapy water, getting into all the crevices with a microfiber cloth. A spray bottle works well for this, but you can even soak the grille in the sink if it’s really gross. Just make sure there are no attached electronic parts when you do.

Wash the filter and set aside both the filter and grille to dry.

Step 2: Remove the housing (optional)

Dusty And Dirty Air Conditioning Cooling System Is Being Cleaning By A Professional Electrician ManZMS/Getty Images

Most air-conditioner manufacturers recommend cleaning the unit without removing the housing, but if your window air conditioner is very dirty or filled with leaves, or if you suspect mold or mildew, taking off the housing may be necessary. Look for screws holding the metal frame to the rest of the unit, and remove them to access the fan, blower motor, drain pan and interior sides of the coils. Save the screws so you don’t lose them! Then move on to the next step.

Step 3: Vacuum the interior

Dirty Dust On Air Conditioner Coil FinsIamMotos/Getty Images

Vacuum the inside, including the evaporator and condenser coils, with your vacuum and brush attachment. The coils will be covered with tiny metal fins, which bend very easily and are sharp, so use caution when vacuuming. Move the brush along the grain of the fins, and use a light touch. If you notice any bent fins, gently straighten them with a credit card or butter knife—they even make special “fin combs” for this purpose.

Step 4: Clean the evaporator and condenser

Dusty And Dirty Air Conditioning Cooling System Is Being Sprayed and Cleaning By A Professional Electrician ManZMS/Getty Images

Fill your spray bottle with dish soap and water. (Hammes recommends distilled water to prevent rust and corrosion.) Put a towel under the coils and start spraying. Gently clean the fins and coils with a toothbrush or other soft brush, moving in the direction of the fins to keep them from bending.

Rinse the coils with plain distilled water. Wipe down the rest of the interior of the air conditioner, including the fan, blower motor and drain pan, with the towel. Check the condensation drain and clear any obstructions.

Step 5: Dry and reassemble

Air Conditioning Cooling System Is Being Cleaning and reassembled By A Professional Electrician ManZMS/Getty Images

Before you can use your just-cleaned air conditioner, it must be completely dry. Prior to closing it back up, wipe down the interior with a clean, dry towel and allow the coils to air-dry for at least an hour. Reattach the housing and front grille panel, slide in the clean (or new) filter and enjoy the cool breeze.

About the experts

  • Michael Rubino is the author of The Mold Medic: An Expert’s Guide on Mold Removal and founder of HomeCleanse, a company that aims to end poor air quality and toxic indoor environments.
  • Brad Roberson is the president of Aire Serv, a company with more than 200 locations throughout North America that focuses on heating and air-conditioning installation, maintenance and repair.
  • Glory Dolphin Hammes is the CEO of IQAir North America, a Swiss-based air-quality technology company that provides information that allows individuals, organizations and communities to breathe cleaner air.

Ally Childress
Ally Childress writes for work and fun, covering topics from technology and trends to cleaning and gardening. She's a licensed electrician with a degree in English, but you can usually find her outside digging in the dirt or taking her dogs to the lake.