How to Clean Your Air Conditioner Before the Next Heat Wave

It's the one thing coming between you and a great summer.

June 12, 2021
Photo by Rocky Luten

The first heatwave of the year hit New England this week, bringing several days of 90-degree temperatures and leaving my boyfriend and I scrambling to install window air conditioners throughout our house. Of course, our ACs were stashed in the basement over the winter, which meant they were covered in dust, cobwebs, and the occasional spider, and we had to clean them thoroughly before popping them in the windows.

If you’re in a similar situation, there are several steps you’ll want to take to clean your air conditioners before installation. Luckily, the whole process should only take an hour or so, meaning you’ll be able to enjoy cool, refreshing breezes before the day is over.

Wipe Down the Exterior

First and foremost, you’ll want to clean the exterior of your air conditioner—especially if you store the unit in a basement, attic, or garage during the off-season, as it likely gets dusty. Wipe down the top, sides, and grill of the air conditioner using a damp cloth, paying close attention to the gaps where the air comes out—after all, you don’t want to be blowing dirt and grime into your home! This step is easy, but make sure you let the pieces dry completely before putting it back together.

Clean (or Replace) The Filter

I’ll admit it: I don’t always keep up with the recommended filter maintenance schedule on my air conditioner. (I know I’m not the only one!) However, it’s one of the most important steps to keep the unit working efficiently. If your AC has a reusable filter, you should be cleaning it at least once a month, as well as before you set it up for the summer. It’s so easy to do that there’s really no excuse not to—simply vacuum off any dust and hair, then wash it with warm, soapy water. Let it air dry, and it’s ready to go back into the appliance.

For units that use disposable filters, you should generally replace them every one to three months, depending on how much you use it, as well as the manufacturer’s guidelines.

Clean the Coils and Straighten the Fins

For this next step, you’ll need to open up the front of your AC. Wipe dirt off of the air conditioner coils with a soft brush or cloth. A can of compressed air can be helpful here, as well. You’ll also want to gently clean the fins—those thin pieces of metal that run vertically inside the unit. They’re fairly delicate and surprisingly sharp, so it’s best to wear gloves and use a soft-bristle brush or a special fin comb to remove dust and dirt from between the slats. If any of the metal is bent, a fin comb (or credit card) will help to straighten it back out for optimal air flow. You can clean the fins on the back of the unit in the same way.

If your coils or fins are particularly dirty, you may want to break out some foam coil cleaner, which will help to remove grease and grime and typically doesn’t need to be rinsed. Again, be sure to let everything dry before reassembling the unit.

Remove the Case for Deep Cleaning

Have you been using your AC for a couple years? If so, it’s probably time for a deep cleaning. It’s actually quite easy to remove the case of your air conditioner—there are usually just a few screws located along the bottom edge. Once the exterior shell is off, you’ll be able to access the inner fans, which often get covered in dirt and dust. You can vacuum out the cavity and wash it with a soapy cloth, or if you have an outdoor area that’s big enough, simply take a hose to it! At the risk of sounding like a broken record, let everything dry completely before turning the unit on.

Managing Mold

Air conditioners can start to grow mold if they’re not cleaned regularly, and if you suspect there’s some growing inside your unit, it’s definitely worth investigating. Inspect the filter carefully and take off the exterior case to get a good look inside your AC. If you spot any mold—typically brown, black, or green spots—you’ll want to clean it thoroughly using a diluted bleach solution and a scrub brush. Wear protective gloves and a face mask while working, and you may want to replace the unit’s filter, just to be safe.

Keeping Your AC Fresh All Summer Long

In addition to the ever-important task of checking, cleaning, and/or replacing your air conditioner’s filter, there’s another (easy) step you’ll want to do monthly while using your AC. When you do filter maintenance, get in the habit of checking the drip pan located in the bottom of the unit under the evaporator coils. This pan collects moisture that drips off the coils, and it can grow mold if not cleaned regularly. All you have to do is soak up any water (there shouldn’t be too much, as long as the drain pipe is functioning properly) and wipe it down with a sponge.

What's your air conditioner cleaning routine? (Do you have one?) Tell us in the comments.

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See what other Food52 readers are saying.

  • Zohar
  • Camryn Rabideau
    Camryn Rabideau
Freelance writer, product tester & baking enthusiast.


Zohar June 20, 2021
I keep spray bottles of a bleach solution by all my window air conditioners. Every time I clean the filter (which is every couple of weeks), I spray the coils, the filter, and the fan outlets. Wait till the solution dries before turning the ac on. Also, I took a hose to one of my acs, as suggested in the article, and it worked like a dream.
Camryn R. June 25, 2021
That's such a good idea! I might have to borrow it from you.