Brown sludge in window air conditioner

Jeremiah is obsessed with saving energy and loves showing others how to do the same.

A window A/C in need of a little cleaning.

jesimpki

Does Your A/C Need Cleaning?

Have you ever wondered why your window air conditioner emits a musty or moldy odor whenever you turn it on? Does it leak water? Have you used it throughout several hot summers?

If so, it may be that your A/C unit has an accumulation of black sludge on the inside, causing odor and blocking condensation from draining from it. It might be time to take the unit out for a good cleaning to remove build-ups of dust, debris, and black sludge.

Why Should You Clean Your A/C Unit?

A/C units work by collecting moisture in the air from the inside of your home to produce cool air. Usually moisture drains out of the unit or is injected into the condenser coils to help cool the refrigerant, but sometimes it gets stuck in the unit, where it stagnates and contributes to the growth of mold and mildew. Aside from the putrid odor this can produce, it can also aggravate allergies.

Another reason to clean the inside of your air conditioning unit is to remove debris that could prevent the drainage of moisture. If the amount of accumulated moisture becomes severe, it can cause water to leak through the unit and onto the window ledge or the floor beneath the unit.

In addition to mold, debris, and moisture, preventing the accumulation of dust is another good reason to clean the inside of your unit. The filter does a decent job of keeping most of the dust out of your air conditioner's internal parts. However, finer dust particles can pass through the filter and collect on the coils inside the unit. If the layer of dust becomes thick enough, it can hinder the unit's cooling capabilities and even cause it to seize up.

What You Will Need

It’s not an extremely difficult task to clean the inside of a window air conditioner.

Here Is What You Will Need:

• Muscle power
• Time
• Garden hose
• Spray attachment
• Light cleaning solution, like dish detergent
• Four-way screwdriver
• Tray

How to Clean Your Air Conditioning Unit

To clean the unit, you should:

1. Move Your A/C Outside

Move your air conditioner outside, placing it on a level surface where you can easily work. Make sure you can reach the unit with a hose.

2. Remove the Air Filter

Begin by removing the air filter and setting it aside. If it needs to be cleaned as well, you can do so at this time by spraying it with a hose or soaking it in a light detergent solution.

3. Remove the Front Panel

Next, remove the front panel. It is usually held in place by two screws, with one on each side. Larger units might have more. After removing them, place the screws in a tray to prevent them from rolling away or getting lost.

Removing the screws on the front panel

jesimpki

4. Remove the Bar

Now, remove the bar from the top of the unit, which holds the accordion panels in place. This can be done by pulling the panels away from the unit until they can be removed from the top and bottom rails.

Note: The accordion panels are still attached to the sides of the air conditioner, so be gentle.

The top rail is usually held in place with three screws. Remove these screws and place them in your tray.

A/C front panel and cover have been removed, exposing accordion panels.

jesimpki

5. Remove the Case Cover

Next, remove the screws holding the top case to the rest of the unit. This portion can be held in place by many screws. Start with the screws at the sides of the unit and remove them. Then begin removing the screws from the top of the unit. Place all of the screws in your parts tray. Then gently slide the cover off the unit. The case may be cut to fit around the power cord so you may need to slide the cover back slightly, then lift it up.

6. Spray With Your Garden Hose

Now, you're ready to begin cleaning the inside of the unit. If mold is present, use some mild detergent and allow it to soak. Use a spray attachment to rinse dust from the evaporator fins (coils at the front of the unit) and blower fan. Spray out any debris from the external fan and condenser fins (coils at the back of the unit), too.

Next, you can begin to spray any debris and sludge from the bottom of the unit. It's easiest to do this by tilting the unit on its side while aiming the sprayer at the bottom and flushing any debris out. Stubborn mold can be taken care of with a soapy cloth or scrubber.

Inside of unit after spraying it out with garden hose.

jesimpki

7. Dry in an Upright Position

Allow your air conditioner to dry for some time in an upright position.

8. Wipe the Nooks and Crannies (Optional)

While your air conditioner is drying, you may also wish to clean the other parts such as the case cover, front panel, and filter. The case cover may have collected pollen and dust as well as bugs and spider webs, especially if it hasn’t been cleaned for a long time.

Hose or wipe out the inside of the cover and wipe the outer surfaces with a soapy rag. The front panel may also have an accumulation of dust around the air intake grill. Hose it out or wipe it with a soapy rag. The filter can be sprayed or soaked in soapy water.

9. Reassemble

Simply follow steps one through five in reverse to reassemble the unit, making sure to reattach the case cover, top rail, accordion panels, and front panel.

Cleaning out a dirty air conditioner can help improve its performance and efficiency. It can also remove harmful dust and mold that may be entering your home.

In addition to cleaning out the inside of the unit, you may also want to straighten any bent fins. The fins are aligned to allow air to blow through them and dissipate heat. When the fins are bent, air cannot flow through them, decreasing the unit's efficiency. A fin comb can be useful for straightening them out, but it isn't necessary.

Front panel after spraying with garden hose to remove dust build-up.

jesimpki

Controlling Build-Up Between Cleanings

You can minimize build-up by regularly cleaning the filter and seasonally cleaning the cooling fins by spraying them with foam cleaning spray.

One other solution to prevent dust, debris, and mold from building up inside the air conditioner is to use an air conditioner pan cleaner tablet to help prevent black sludge from building up on the inside and avoid bad odors. Avoiding sludge will also reduce the chance that your unit will get clogged and leak condensation in your home.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

Chas Briggs on June 03, 2019:

mix hydrogen peroxide and listerine that is a great safe germ killer

black mold on May 25, 2019:

1 part bleach 10 parts water & about teaspoon of dishsoap (dawn) for a powerful mold cleaning solution.

Silvia on August 01, 2018:

WHen using a store baught spray cleaner, do i have to wait a while before turning the ac back on?

Tellher on February 24, 2018:

I have a similar situation. The ax won't come up because some of the connection were wet when I plugged it. What do I do?

Jeremiah Simpkins (author) from Pulaski, VA on August 03, 2014:

Sorry for the delay, do you mean like the electronics were wet? There is the possibility that, unless the unit used simple mechanical relays/thermostats that any control panel (like digital temperature and fan speed controls) could short out. If somethings like that happens, it may or may not work, and I'm leaning towards not, after drying out. Good luck!

adrian on July 22, 2014:

if the unit was wet an was working then shuts off will it work when it dries out completely?

Joseph Chen from Houston, TX on July 14, 2014:

Thanks. This is a useful information. I never had tried doing stuffs like that since I am not an expert to it. Next time, I won't hire someone just to clean my air condition unit.

Jeremiah Simpkins (author) from Pulaski, VA on July 04, 2014:

Dudemanning, I'd vacuum any dust off of them but otherwise, avoid getting any connections/control panels wet directly and be sure to let everything dry for a few hours.

Dudemanning on July 02, 2014:

What about the wires and everything else?

vibesites from United States on May 21, 2013:

I admit I haven't bothered to take out my air condition for cleaning since I bought and had it installed, although sometimes. I just don't know where to start! I will have this as a manual. Thanks for sharing! Up and useful. :)

Diana L Pierce from Potter County, Pa. on March 25, 2013:

Good tips. Thanks. I'm sharing these.

Jeremiah Simpkins (author) from Pulaski, VA on May 23, 2012:

diylearner, both the fan motor and the compressor are sealed units. You don't have to cover them. Just make sure to allow the ac enough time to dry before using it again.

diylearner on May 20, 2012:

Amazing details jesimpki.

This might be an obvious answer but just wondering, do I have to be careful about not putting water on the motor etc ? I remember seeing my neighbor cover a part of the ac with a polybag once. Thanks

How do I clean the sludge out of my air conditioner?

Why is there slime in my window air conditioner?

Is it dirt or mold in my window AC?

How do you get rid of dirty sock syndrome on a window air conditioner?