Skip to main content

How to Clean a Window AC Unit

By December 21, 2020Home Maintenance
How to clean a window AC unit

Many homeowners choose to put a window AC unit in specific rooms in their home to keep the room cooler. Some homeowners will install them in parts of the house that stay too warm, even though they have central air.

The outside of the unit can weather Mother Nature.  However, the inside part of the unit needs to be clean.  Like most appliances, maintenance is key. 

How do you clean a window AC unit? Take the unit out of the window, take off the front cover and take out the air filter, clean the coils, clean the fins, and wash the fans and pan. There are a few steps and different alternatives.  Let’s take a look.

Why This Matters for Window AC Units

Some homes, depending on where you live, don’t need central air or the home is too old to have it.  Instead of the expense of installing it, many will choose window AC units.  To keep these working efficiently, cleaning is important.

How to Clean the Window AC Unit

There are a few different ways to clean the Window AC unit.  As always, safety is a concern so make sure the unit is unplugged.

Step 1: Take Unit Out of the Window

Unplug the unit– Then, remove the plastic filter/trim panel that holds the AC unit in the window and take the unit out of the window. Take it outside so you have room to clean it.

Take off front cover and take out the air filter.
Dirty air filter

Step 2: Take Off Front Cover and Take Out the Air Filter

Look at the air filter.  If the air filter is dirty, use 3 to 4 drops of dishwashing detergent in a water bottle mixed with water and spray it on the filter to clean it.  Then spray it on the front cover.  The dirt should start to come off. 

If not, go ahead and spray it with water and you can let it air dry.  The filter should be cleaned every month that the window unit is in use.  In addition, if you don’t, you won’t get the air through there and you may have more issues.

Step 3: Clean the Coils

There are two sets of coils on a window AC unit.  The evaporator coil in the front faces the room and the condenser coil that is in the back faces the outdoor elements. To clean the coils, you can use coil cleaner after you vacuum the dust out.

Spray foam cleaner on the coils with a brush made of nylon bristles. Then, brush it to get the dirt loose.

Clean the fins
Fin Comb Source: Amazon

Step 4: Clean the Fins

We aren’t talking about fins on a fish; we are talking about fins that are under the cover of the AC unit.  Be careful with the fins, as they are sharp so wear leather gloves so you don’t get cut.  Use a fin comb to clean and straighten the fins.

What If the Fins Are Bent When I Clean a Window AC Unit

If you notice the fins are bent while cleaning them, use a fin comb to straighten them.  It is essential that they are straight to let the air flow out.  If you are short on time, an old credit card can work as well.

  1. Insert the card or comb into an area that is not bent
  2. Then run the card or comb through the fins and straighten them out as you go.

Step 5: Wash Fans and Pan

There are two fans on a window AC unit.  One is near the evaporator and the other one is a fan with blades near the condenser. They both get dirty and need to be cleaned.  You can use the same concoction used above and also a rag to clean the dirt off.

The pan catches the water that drips off the coils.  Make sure to wash out the pan and check the hole isn’t clogged. You need the hole to be free of debris so the water can drip into the pan.  If not, it will back up into the wall unit and come out on to the walls. This will leave you with problems with mold in the home. 

Step 6: Clean Back Cover

  • First, take off the back cover and spray the backside cover too.
  • Then, spray coil cleaner in the inside but away from the knobs to clean
  • Wait 5 minutes and use the brush to clean the dirt off.
  • Last, spray water on the back cover and backside, avoiding the knobs and electrical areas.
  • After cleaning, pick up the unit and dump the water out that has accumulated and leave it to dry for 24 hours.

Problems with Window AC Units

Problems with Window AC Units
It is important to clean and change the Air conditioner filter Source: Amazon

Air Conditioner not blowing cold air- The Department of Energy recommends keeping the air filter clean. Moreover, if the AC unit is not blowing cold air, it could be a few reasons:

  1. Dirty air filter – buy a replacement if you can’t get it clean.
  2. Evaporator, condensing coils, or cooling fan are clogging – this can lead to the growth of mold. 
  3. Water dripping out of the unit- the hole is clogged and needs to be cleaned out.

How to Clean Window AC Unit for Winter: Check the Seals

Inspect the seals between the air conditioner and window frame.  You want to make sure that before winter approaches, the seal is working.

Maintenance to Clean Window AC Unit

Clean the unit once a month that it runs.  This is important as the air filter will be dirty and not allow the cooler air to flow through.  It can also cause the window unit to freeze up.

You can vacuum the filter if it is just dusty.  However, if it has a lot of grime, then you need to clean it with the concoction listed above. Check the owner’s manual for the type of filter so you can replace it when it is time.

How to Clean Window AC Unit: Store the Window AC Unit When Not in Use
Cover for window AC unit

How to Clean Window AC Unit: Store the Window AC Unit When Not in Use

In colder climates where you might use the window unit seasonally, store it away where it is safe and dry.  Also, leaving it in the window all year long uncovered can cause it to freeze and dirty quicker, and you don’t want that if it is not being used. A good waterproof and weatherproof cover is great if you don’t want to take it out of the window.

When to Think About Replacement of the Window AC Unit

You may need to replace the window AC unit if:

  1. AC unit making odd noises, even after you clean it
  2. Your unit is 8-10 years old and having issues
  3. You are calling a professional for help often and on a first name basis
  4. Your AC unit is not cooling down the house and causing you frustration

When to Call a Professional

  1. If you need help cleaning the window unit
  2. You have leaks or not feeling cold air come out
  3. The window unit stops working


Window AC units are nice to have when you live in a climate that doesn’t require central air, or have a home that doesn’t have central air.  It is cheaper to run but does need maintenance.  Do you have questions about window AC units?  Or need help with cleaning the unit?  Let us know so we can help!