Nobody likes mold! Whether you’re a homeowner or a renter, mold is a dreadful sight! Not only that, but it can also pose a serious health risk.

One unexpected place that can grow mold is your air conditioner. When the air is passing through the room, it can pick up some mold.

A good sign of black mold is its characteristic smell when you turn on the AC. Sometimes you can even smell it when the AC has been on for some time. If you’re allergic to mold, you’ll be able to tell when your allergies are triggered and you start sneezing or coughing. It is especially dangerous for those with severe allergies or asthma.

Sometimes you can see the mold forming on the air conditioner’s filter or the inside of it. Either way, once you’ve figured out you have mold, you need to get rid of it!

But first, let’s talk about what kind of mold grows in window air conditioners.

What Kind of Mold Grows in Window Air Conditioners?

6 common types of mold grow in window air conditioners.


Commonly referred to as black mold, this type of mold has a greenish-black color. It usually grows on paper, lint, dust, fiberboard, and gypsum board.


This type of mold is most common in summer and requires wet conditions to grow. You can find it in humidifiers and stagnant water.


Much like Fusarium, Acremonium needs a wet environment. It often occurs in hay or other dead plants. You can also find it in building materials that have been in water, or AC units. One source of Acremonium at home is humidifier water.


This kind of mold is very aggressive. It grows in conditions that remain wet for long periods, such as air vents. It looks like spores and multiplies very quickly, thus posing a real threat to your home.


This type of mold is most commonly found in water-damaged building materials. You can also come across Alternaria in flooded areas and humidifiers.


Mucor is the mold that you come across on the windowsill by your air conditioner.

Common Causes of Window Air Conditioner Black Mold

Mold comes from mold spores, which are everywhere. You cannot get rid of all the mold spores in your house. Even if you did, it would be completely pointless, as more would enter every time you open a door or a window.

Luckily, mold spores by themselves are not threatening. They only pose a problem when they grow into mold and multiply. Since you can’t get rid of mold spores altogether, you need to monitor the growth of mold in your house.

Here is how mold spores can grow into full-blown mold in a window air conditioner.

  • Mold spores are blown into the AC unit.
  • Mold needs a wet environment to grow. One way to prevent mold is to control the moisture in your home. But since your AC gets rid of the moisture in the room, it collects a lot of it. Thus, mold in window air conditioners is very common.
  • Much like people, mold needs food to survive. That is one of the reasons you can often find mold on actual food items. One way to starve the mold is to keep your AC clean at all times.

Generally speaking, air conditioners are not the perfect place for mold, especially if you clean yours regularly. However, they are a breeding ground for dust, which mold can feast on and grow.

Ways to Get Rid of Mold in Window Air Conditioners

You should always clean your air conditioner in a well-ventilated room. Note that you might be using bleach. Be careful, as it’s very dangerous if it gets into your eyes or mouth, and you cannot get it off your clothes.

First, you need to unplug the unit and remove the grille cover. Most of the time it snaps off, but in some situations, you might need to unscrew it. Then you should shine a flashlight into the air conditioner and look for mold. It can appear green, brown, or black, and is sometimes fuzzy. One common type of mold also has a gray or white color.

If you find a few traces of mold inside, you’re in luck! You can probably just clean that off. However, if over 1/3 of the unit is covered with mold, you should consider replacing the whole AC.

You can use Tilex spray for black mold. Spray it onto the mold, wait a few minutes, and wipe it off with a cloth of your choice.

Here are the detailed instructions you can follow to get rid of black mold in window air conditioners.

  • Start by drawing approximately 2 inches of water in a large sink or bathtub. Add a healthy amount of dish soap. Mix the soap with the water to create a soapy solution.
  • Use a wet cloth to wipe the outside cover of the AC. Clean it well to avoid getting any dirt inside once you open the cover.

  • Remover the AC grille and the filter. You might need to unscrew it, or just slide it out. Proceed according to the design of your air conditioner.
  • Put the filter in the sink/tub with soapy water, or spray it with Tilex and let it sit for 15 minutes or longer.

  • Use a nylon brush to scrub both sides of the filter. Rinse it and shake the water off. Then, dry it with a towel and let it sit until it’s completely dry.
  • Clean the cover and the metal grille with a vacuum extension and a hose. Clean the whole cover thoroughly, and if there is still dirt left over then wipe that off with a wet cloth.

  • Let all the parts dry completely before you reassemble your air conditioner. Then you can plug it back in and turn it on. If there is some stuff coming out of the AC, don’t be alarmed!

Now that your AC is clean, all you need to do is make sure it stays dry and clean.

Ways to Prevent Mold in Window Air Conditioners

Unfortunately, once you’ve had mold, there is a high chance it will return. There is nothing you can do about that unless you want to spend money on a brand new AC.

That happens because mold spores can remain in the deep parts of the AC. To prevent mold from forming, get rid of dust regularly. Make it a habit to clean the inside of your air conditioner every few weeks.

If there is no dust in the unit, the mold won’t get a chance to grow. You can blow dust out of the back of the AC with compressed air. Some people cover their air conditioner with a towel when they’re not using it.

If you have AC in your house, you must also have a drainage system that leads to a drain tile or a utility sink. Make sure the system is working and doesn’t allow moisture in the AC. If your drains get clogged, your whole house can get flooded.

To make mold prevention easier, you can schedule regular cleanings and maintenance checkups. Don’t forget about HVAC maintenance when the seasons are changing. Let your air conditioner prepare for the change in weather in due time.

Window air conditioners are especially good for mold, as they are dark and warm on the inside. To avoid mold outbreaks, conduct regular checkups and clean the unit every few weeks.

If you’re looking to change your air conditioner, get one with humidity control. That takes all the work off your shoulders and lets the AC control the levels of moisture.

Ending thoughts on what kind of mold grows in air conditioners

Many homeowners have faced mold before. Not only is it ugly and unhygienic, but it is also threatening to people’s health.

Getting rid of mold can be quite easy if you catch it right away. It will get harder as it begins to grow and spread.

If mold gets into your AC, it can spread throughout the house. To avoid that, it’s best to not give it moisture and nutrition. Conduct regular checkups and clean your air conditioner!

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