How to clean a window AC unit: 7 essential steps

This summer, temperatures soared across the countries of the Northern Hemisphere, making it the hottest summer on record. In many cities and states, it has been common for homes to be built without air-conditioning, but we expect that will soon change. With temperatures continuing to rise, we will see more and more people seeking the cooling aid of window AC units.

Tools & requirements

- Washcloth 

- Warm water

- Vacuum with brush attachment

- Hydrogen peroxide

- Spray bottle

- Fin comb (or soft bristle brush)

- Gloves

- Knife (optional)

- Coil cleaner (optional)

- Mild soap/detergent (optional)

- Condensed air (optional)

- Screwdriver (if needed)

Even the best window air conditioners require maintenance to keep it in working order. Plus, the cleaner it is, the less energy it uses and the less likely it’ll become a breeding ground for mold and mildew.

"It's important to regularly clean your air conditioner," says Meaco co-founder Chris Michaels, "to ensure the appliance is working effectively and the cool, dry air that’s blown into the room is as clean as possible."

The air treatment-expert explains that, when AC units pull in air from the room, "dirt present in the air and the air conditioner’s surroundings will collect on its filters, and this builds up over time." To avoid this, and to keep the air as fresh as possible, the key is to clean the window AC unit regularly.

Deep cleaning a window AC unit is not as difficult as it may seem. We’ll break it down for you in a step-by-step guide so that you can handle the job on your own and enjoy sweet, cool air blowing around your home.

Quick steps: How to clean a window AC unit

1. Unplug the window AC unit and remove the front panel

2. Clean and/or replace the filter

3. Vacuum the interior

4. Wipe down the exterior and the grill

5. Comb the fins and dust the coils

6. Mildew and mold prevention

7. Let everything dry before reassembling the unit

Step by step guide: How to clean a window AC unit

1. Unplug the window AC unit and remove the front panel

(Image: © Alamy)

To start your deep cleaning, you’ll need to turn off and unplug the window AC unit. From there, remove the front panel. Some are held in place by screws, clips, tabs, or some combination. If need be, grab a screwdriver and remove the screws. Put them in a safe place so you don’t lose them.

You may want to set a towel on the ground below the unit so that you can place dirty or clean items on it as you work.

2. Clean and/or replace the filter

(Image: © Alamy)

Remove the air filter from the window AC unit. The user manual will provide specific instructions on how to do this.

Use a vacuum with a brush attachment to remove dust, dirt, hair, and any other sediments clinging to the filter. Clean it more thoroughly with running water – either a sink with high pressure or a garden hose. Let the filter dry as you clean the rest of the window AC unit.

"If the filter is blocked then that airflow is reduced and less air hits the cooling coils," says Meaco MD Chris Michaels. This results in the machine not being able to provide as much cooling for you.

"Cleaning the air filters frequently will prolong the life of your portable air conditioner," Chris explains. Not only that, but you’ll also need to replace it on occasion - if it's looking worse for wear, it might be time to replace it.

3. Vacuum the interior

(Image: © Alamy)

Use the vacuum on the interior of the window AC unit. You want to make sure that you vacuum around the bottom, the fan, the blower, evaporator, and condenser. Use a brush attachment on the vacuum hose to do a once over on the aluminum fins. Vacuum in the same direction as the fins, trying your best not to damage or bend them.

4. Wipe down the exterior and the grill

(Image: © Alamy)

Dip a washcloth in warm water (adding a small amount of mild detergent or soap is optional) and use it to wipe down the exterior of the window AC unit. Pick up the grill that you set aside and clean it off as well. Get into the gaps and grooves to remove any dirt and dust that has built up. If you find that you are unable to clean the grill thoroughly, you can use a garden hose to rinse it down. Let it dry as you complete the next steps.

5. Comb the fins and dust the coils

(Image: © Alamy)

Window AC units have an evaporator coil on the room side of the unit and a condenser coil on the back facing the outside. These coils move the heat from inside the room to the outside. They are covered in aluminum fins and are very important in the cooling of your home.

The fins are sharp so it’s best to wear thick gloves during this part of the cleaning. Use a fin comb or a soft-bristle brush to comb any remaining dust and dirt from the aluminum fins (this Fin Comb Set at Amazon would work well).

Run the brush or fin comb in the same direction of the fins being careful not to bend them. If you discover any bent fins, use a knife to straighten and/or move them back into place.

If you have a bottle of compressed air, spray into the fins and around the coils on both sides of the unit. Blow any remaining dust from near the fan and the motor.

If the fins of your window AC unit have a lot of thick, deep build up, you may want to use an air-conditioning-safe coil foam cleaner, like this QwikProducts Foaming Coil Cleaner at Amazon.

6. Mildew and mold prevention

(Image: © Alamy)

Pour some hydrogen peroxide in a spray bottle and spray the interior and the exterior of the window AC unit. Use a dry rag to wipe everything down. This will help to prevent mildew and mold from forming until the next deep clean. Keep the solution on hand for the last step.

7. Let everything dry before reassembling the unit

(Image: © Alamy)

You’re almost done – you just have to reassemble the unit. Place the air filter back in and put the cover back on. Then grab the spray bottle with hydrogen peroxide and spray the grill or anywhere air flows in and out of the unit. Let it dry before you plug the unit back in and turn it on.

FAQs

How often should a window AC unit be deep cleaned?

Although you’ll need to clean your AC window unit’s filter at least once a month, we recommend a deep cleaning at least twice a year – before and after the summer season.

Plan to do a deep cleaning in spring right before you start using the AC window unit and then again in fall, when you effectively stop using the AC window unit in favor of a heating source. In doing it this way, the unit will be clean in the summer and won’t build up more mildew or mold in the winter.

Can bleach damage my window AC unit?

While bleach is great at removing mold and mildew around your home, it is corrosive to metals. Using it on your A/C window unit can cause damage, which is why it’s better to use a 3% hydrogen peroxide solution to prevent mold and mildew from forming on the unit.

Is it ok to spray water on my window AC unit?

Using water to clean your window AC unit should be fine, especially if you use a dishrag or washcloth to clean it off. Just make sure that the window AC unit is turned off and unplugged from the wall.

Final thoughts

Cleaning a window AC unit is not as scary as it seems. While it may take you about 30 minutes to complete this chore, you’ll be glad you did.

Your window AC unit will last longer, run better, and blow cold and clean air through your homes. With sweltering temperatures such as we’ve experienced in the last few years, a deep clean twice a year is well worth the time and effort.