how to clean window ac unit

Having a window air conditioner is a life-saver during the hottest months of the year -- but all of that heavy-duty use can really take a toll on your AC unit. In order to keep your window air conditioner in good working order, it's important to clean it regularly.

By keeping your air conditioner clean, you'll prevent mold and mildew from growing inside and get more long-term value out of your appliance. Plus, a well-maintained window AC unit uses less energy than a dirty one.

However, cleaning a window air conditioner might seem daunting if you've never done it before. Fortunately, the process isn't as complicated as it may seem. With the following tips, you can keep your AC unit clean, functional, and energy-efficient.

Gather your materials

You'll need a few items from around the house to give your air conditioner a thorough clean. Before you get started, grab the following materials:

Warm water
Mild soap or detergent
Reusable cloth
Drip tray to place beneath your unit
Spray bottle filled with 3% hydrogen peroxide
Fin comb or soft-bristle brush
Compressed air
Screwdriver

1. Clean the filter

Cleaning the filter inside your window AC unit is the most critical thing you can do to keep it working smoothly. It's a good idea to wash the filter monthly, even if you don't clean the entire appliance. Here's how to do it.

First, make sure your air conditioner is unplugged, then take off the front panel and remove the filter. If it's covered in dust or hair, use a vacuum to clear away as much debris as you can. From there, wash your filter with warm, soapy water and set it out to dry. Wait until it's fully dry before putting it back into your window AC unit.

It's also a good idea to replace your air conditioner filter regularly. The exact frequency will depend on how much you use your AC and environmental factors, but you should aim to swap your filter out every six weeks to six months.

2. Wipe down the grill and exterior

While your filter is drying, wash the grill with warm water and mild detergent. Or if you don't want to wash it, you can instead use a damp reusable cloth to wipe it down -- just make sure to clean thoroughly in between the gaps where air comes out. Let it dry completely before reattaching it.

Once you've cleaned the grill, wipe down the top and sides of the air conditioner. Take care to get inside of small spaces where it's easy for dirt and dust to collect. Wait until the grill and exterior are fully dry before running the unit.

3. Dust off the fins and coils

Now it's time to roll up your sleeves and get inside your AC unit. You don't need to dust the fins and coils every time you clean your air conditioner, but most manufacturers recommend doing it quarterly or semiannually.

First, take a fin comb or soft-bristle brush and gently comb the aluminum fins inside your AC. Take your time during this process because the fins bend easily and can be sharp. If you notice any bent fins, softly move them back into place.

Next, spray your can of condensed air inside the unit to dust off the coils. You should be as thorough as possible to remove any debris that could be preventing your appliance from working correctly.

4. Clean out the tray and drain

Finish the interior clean of your window AC unit by emptying the drip tray and clearing the drain. To remove debris or dirty water from your tray, grab a wet-dry vacuum (if you have one) or a damp cloth and pull out everything that's collected inside. Leave it to dry before reassembling.

Finally, check the drain to see if anything is blocking it. Use your cloth to wipe around the opening and make sure there's a clear pathway for water to exit your unit.

5. Reassemble and spray cleaner on your unit

After you've cleaned and dried everything, it's time to reassemble your window AC unit and give it a final spray to prevent mildew from growing.

Grab your hydrogen peroxide spray bottle and apply the solution to the areas where air flows in and out. Wait for the peroxide to dry before using your appliance -- and you're done! Not only will you breathe in cleaner and colder air, but you'll extend the life of your air conditioner as well.

Final tips

In addition to cleaning it regularly, there are other steps you can take to keep your air conditioner in proper working order. For instance, remove it from your window and store it inside during the winter months or when you won't be using it for long periods of time.

If this seems like more work than you're willing to put in, you can always hire a professional to clean your window air conditioner for you. To find someone, ask your friends and family for referrals or check with reputable service providers in your area.

But whether you decide to bring in an expert or clean it yourself, just make sure to stick to a regular cleaning schedule. At a minimum, clean your filter monthly and spray your unit with hydrogen peroxide to fend off mildew.

More air conditioning advice for 2021

How to choose a cool AC window unit
Portable air conditioners: How to buy the right one and stay cool
How to find the best smart window air conditioner

Get the CNET How To newsletter

Receive expert tips on using phones, computers, smart home gear and more. Delivered Tuesdays and Thursdays.