How to clean mold on styrofoam in air conditioner

It is uncommon to find mold on styrofoam. That is why when you notice mold on styrofoam in your air conditioner, you first wonder how it got there and how to clean it.

Generally, styrofoam does not absorb water or moisture, making it an unfavorable environment for mold growth.

However, mold can grow on styrofoam in your AC unit if there is a combination of excessive moisture and organic material like dirt.

There are several ways to kill mold on styrofoam in an air conditioner. One of the most common methods is using dish soap and water.

Alternatively, you can mix water with a bleach solution before applying it to the styrofoam.

Those who prefer natural methods can use a damp sponge or a mix of vinegar and water.

Should I remove the styrofoam from an air conditioner?

Styrofoam is part of an air conditioner, and its function is to offer insulation and prevent moisture buildup.

Since it is an essential part of the AC, you do not need to remove it.

However, there are instances where you may have to remove it, including when replacing it entirely. But always allow an expert to replace it.

How to clean mold from a portable air conditioner

Before cleaning, understand that styrofoam’s chemical and physical properties mean you have to be careful with the cleaning substance you choose.

Some chemicals act as solvents on styrofoam and can dissolve or damage the material.

However, using the following methods, you can clean mold on styrofoam in an air conditioner without damaging it.

1. Use dishwashing soap

Dishwashing soap and water are enough to clean styrofoam and eliminate mold. Here is what to do:

  • Unplug your AC unit from the power source.
  • Remove the styrofoam from the AC if it is removable. In the case of a window AC, use a screwdriver to unscrew it from the frame.
  • Pour some water into a large bucket.
  • Add several drops of dishwashing soap into the water.
  • Dip a sponge into the solution until wet.
  • Gently clean the styrofoam, paying attention to the mold.
  • Rinse the soap from the styrofoam once clean.

You can now allow the styrofoam to dry before installing it on the air conditioner or returning the AC.

2. Use vinegar

apple cider vinegar

Vinegar can clean styrofoam and eliminate mold because of its antimicrobial properties. Here is how to use it:

  • Mix equal parts of water and distilled white vinegar in a spray bottle.
  • Attach the nozzle and shake well to combine them.
  • Spray the mixture on the styrofoam, paying attention to all sides.
  • Wipe it up using a sponge or paper towel.

Distilled white vinegar can also help eliminate dirt from styrofoam. Alternatively, you can use undiluted vinegar or any vinegar solution to kill mold on styrofoam.

3. Use lemon juice

Image by: Flickr/Kiem Soat

Lemon juice has acidic properties that break down mold spores, making them easy to remove.

Do the following:

  • Mix one part lemon juice and two parts water in a spray bottle.
  • Replace the nozzle and shake the contents.
  • Spray the solution on styrofoam.
  • Wipe it up using a sponge or paper towel.

The treatment can also help eliminate bacteria from styrofoam.

4. Use bleach


It would be best if you took extra caution when cleaning mold on styrofoam using bleach. Ideally, ensure to wear rubber or any non-porous material.

Also, avoid mixing bleach with ammonia or other cleaners. Chlorine bleach is best for this purpose.

  • Mix equal parts of chlorine bleach and water in a spray bottle.
  • Shake the mixture.
  • Spray it over the styrofoam.
  • Let the treatment sit for at least 20 minutes.
  • Scrub using a soft sponge.
  • Rinse it off.

Finally, allow the styrofoam to dry before installing.

5. Soak styrofoam in water

Mold can grow on styrofoam with excessive moisture and an accumulation of organic material like dirt. Therefore, soaking styrofoam in water to eliminate dirt ensures no mold growth.

  • Pour some water into a bucket. The container should be large enough to fit your AC’s styrofoam.
  • Add one cup of your preferred detergent or cleaner.
  • Submerge the styrofoam in the water.
  • Allow it to soak for at least five minutes.
  • Remove the styrofoam from the water.
  • Allow it to dry for the entire day.

You can opt for this treatment as often as possible to prevent the buildup of dirt on styrofoam, which ultimately leads to mold growth.

Can black mold grow on styrofoam?

Styrofoam does not allow the absorption of moisture. Therefore, it is rare to find black mold growing on it.

However, if the styrofoam is dirty and there are droplets or leakages, the environment will be favorable for black mold to grow.

Does vinegar kill mold in an air conditioner?

Vinegar is an effective solution for cleaning an air conditioner since it can kill mold and eliminate dirt.

It has antifungal and antibacterial properties, making it the best treatment for different types of mold.

Can I spray bleach in an air conditioner?

Bleach has antimicrobial properties that make it the best for cleaning air conditioners. However, avoid using bleach too often to clean your AC unit.

Instead, consider diluting your bleach solution by mixing a quarter cup with one cup of water and cleaning the air con.

You will then have to use a mold spray for a window air conditioner to get rid of mold.

Wrapping up

Mold can occupy styrofoam if combined with excessive moisture and an accumulation of organic material like dirt.

You can eliminate mold on styrofoam in your air conditioner using dishwashing soap, distilled white vinegar, and bleach.

However, ensure to unplug your AC unit before cleaning. Also, avoid harsh chemicals that can dissolve or damage styrofoam.

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