Your Window AC is Filthy—and May Be a Mold Magnet. Here's The Best Way to Clean It. (2025)

A good window AC unit is the difference between a fun summer and a miserable one. Just like a refrigerator or dishwasher, the appliance needs to be properly maintained in order to keep you cool and your electricity bill low.

Over time, dust and debris build up inside your window AC unit and cake onto components. This disrupts air flow and makes the compressor and blower work harder than they need to. Cleaning your window AC keeps it running efficiently and improves performance, which can help extend the life of the unit.

How often should you clean your window AC unit?

Clean your window AC unit about every 60 days if it's in continuous use. If the unit doesn't serve as your heater, store it in the off season so dirt doesn't accumulate. If you do take it out of your window, clean it before re-installing.

How to Clean a Window AC Unit

First, gather a few supplies.

Use mild dish soap, hydrogen peroxide solution, or all-natural cleaner like Mrs. Meyers. Don't use common household cleaning agents like alcohol, bleach, or vinegar because these corrode and damage metal.

You'll also need a vacuum with a hose attachment, rag or sponge, and a soft brush or fin comb. I also use a small Swiffer duster after it's all said and done because I'm allergy riddled and it gives me peace of mind.

Start with the grille cover.

Unplug your window AC unit and remove the grille cover. Sometimes they're screwed in—in which case you'll need a screwdriver—though some have clips, hooks, or fasteners that can be undone by hand.

Spray the grill cover with the cleaning solution and then rinse it with water. If you have access to a hose, just hose it down outside. I don't have one at my apartment so I soak the grille in the sink with the cleaning solution while I clean the rest of the unit.

Clean the filter and replace it periodically.

My dad always said changing the oil is the life of a car—same can be said for changing the filter on your window AC unit. Not replacing or cleaning the filter is a surefire way to inadvertently damage your unit.

You'll see the air filter when the grille cover is removed, though, in some units, the filter is housed in the grille cover itself. Remove the air filter from either the unit or the grille. Check the owner's manual to see if your window AC unit uses a reusable or disposable filter. Either way you should replace or clean your filter every four to six weeks.

If the filter is reusable, vacuum it to remove the debris, then wipe it down and set it aside to dry. Some may leave it at just hosing it off but I like to use the cleaning solution here as well. Mold spores can grow on the filter as they can on the grille so it doesn't hurt to thoroughly clean both.

Vacuum the unit and wipe down the interior.

Use a brush or small vacuum attachment to vacuum the dust and dirt that collects inside the window AC unit. Be sure and hit the blower, condenser, fan, compressor coils and evaporator coils. Don't press too hard on any of these components with the vacuum attachment so as not to damage them.

After vacuuming, wipe down the interior with your cleaning solution. If you opt to use an AC coil cleaner for the compressor and evaporator coils, you won't need to rinse them after.

Straighten out the fins.

The fins on your evaporator and condenser can get bent over time, which causes your window AC unit to run inefficiently. You can use a knife, but we recommend investing in a fin comb to straighten them out. Run the fin comb in the direction the fins need to be straightened. It may take a couple of passes in order to straighten all of them completely.