How to Clean a Moldy Window AC Unit

Mold is an issue no homeowner wants to deal with. But when it’s in your air conditioning unit, there is a way to remedy it, and it’s important to do so as soon as it’s discovered.

Mold can cause serious health issues and can grow inside your window AC unit, picking up spores and sending them into your home’s air.

Signs of Mold

How do you know if mold is lurking in your window air conditioner? Be on the alert for a musty smell when the unit is running (especially after it has stopped running for some time), you or other family members experience allergy symptoms when inside your home, or you may even see mold in or on the air conditioner.

The Cleaning Process

First, you’ll need to gather these supplies: protective eyewear, a face mask, gloves, water, laundry detergent, bleach, mild dish soap, a five-gallon bucket, cloth, scrub brush, screwdriver, and vacuum cleaner with attachments. You should only clean the unit in a well-ventilated area. Avoid bleach getting in contact with your skin, mouth, and eyes. Now, follow these steps:

  • Put on your safety gear.
  • Turn off the AC unit, unplugging it from its power source, and move to a well-ventilated area.
  • Remove the front body grille. In most cases, this is done by pulling forward and pushing down slightly. If this is screwed in, remove the screws first.
  • Remove the filter located in the front grille. If it’s disposable, replace it with a new one. If it’s washable, put it in your sink and gently spray with laundry detergent.
  • Fill the sink with hot water high enough to cover the filter and let it soak for 15 minutes. After, use your scrub brush to clean both sides. Rinse with clean water and hang to dry.
  • On the unit, remove screws from the metal cover behind the front body grille and lift directly upwards.
  • Use the vacuum and related attachments to clear out as much dirt and debris as possible. Wipe any visible mold growth away.
  • In your bucket, mix 1/2 cup bleach, 1 tablespoon dish soap, and three gallons of hot water. With a cloth, brush, or sponge, soak up the mixture and scrub any moldy areas well. Let the solution sit on the areas for about 10 minutes, then rinse with water and a damp rag.
  • Let the conditioner, filter, grille, and metal cover dry completely before reassembling the unit and running it.

Need additional air conditioning help? Call A&T Heating and Air Conditioning in Mohnton, Berks County, PA at 484-516-1017 or visit us online at

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