Air Conditioner Mold

Air conditioner mold contributes to mold symptoms in virtually every home I investigate. I’ve had clients suffer asthma attacks and be rushed to emergency rooms due to hidden air conditioner mold.

Black mold and white mold

Black mold and white mold inside of window air conditioner

Mold in window air conditioner coils and on the front grills is the worst. The photo above shows both black mold and white mold growing on the louvers on the front grill of a window air conditioner. Typically, air conditioner mold is not this blatantly visible. Unless someone has a very smelly air conditioner, most homeowners are unaware that hidden air conditioner mold is affecting their indoor air quality.

Air conditioner mold is hidden inside ducts

Air conditioner mold hiding inside ducts

Air conditioners cool our air and simultaneously pull moisture out of the air so it doesn’t feel so humid indoors. What many people don’t realize is that because they circulate air, they also attract airborne microscopic particles that provide food for air conditioner mold. The microscopic dust particles consist primarily of dead skin cells sloughed off of humans. They are easy for mold to digest and are full of nutrients to enhance growth.

Hidden mold inside of wall units, like those that are common in hotel rooms and older buildings, and mold in window air conditioners, is caused as a result of those nutrient-rich particles sticking to the wet surfaces inside of air conditioners.

An interior mold inspection should be performed at least once per cooling season or more frequently if an air conditioner is used all year long.

Inspect your filter

I frequently discover mold in window air conditioner filters, filters that are plugged with dirt, and filters that are missing altogether. Clogged or missing filters will ultimately cause mold to grow in the filters and on the cooling coils, as well as increase your electric bill.

mold in air conditioner on coils

The photo above shows mold in air conditioner coils that grows as a result of operating a window air conditioner without a filter in place.

Air conditioner filter media

If you don’t have a filter, you can either purchase one from the manufacturer or purchase a roll of air conditioner filter media from a local hardware store, as shown in the photo above. The media can easily be cut with scissors to fit in any air conditioner.

Air condition mold and dust in filter media

The photo above shows a plugged filter being lifted up from behind the front grill. This is where the filters are always located.

Filters should be inspected every 30 days. Depending on the air conditioner design, the filters either need to be removed and washed, or replaced.

Air conditioner mold is hidden in the drain pan

Air conditioner mold and bacteria is hidden in the drain pan

When installing wall and window air conditioners, some are not pitched correctly downward to safely allow water in the condensation collection pans to drain to the outdoors. Additionally, due to lack of maintenance, the drain holes in the water collection pans located underneath these air conditioners can also become plugged with bacterial growth.

In either of these instances, water can back up and leak into walls resulting in additional mold growth. Moreover, one of the bacteria that grows in water collection pans is Legionella. This is the bacterium responsible for legionellosis, a progressive and potentially fatal pneumonia, i.e. legionnaire’s disease.

Infrared thermal image showing air conditioner causing mold in the bedroom of a new condominium.

The photograph above is an infrared thermal image of an air conditioner in a bedroom wall in a new condominium building. The blue color shows how the incorrectly installed unit has been leaking the drain water into the wall system below which then caused an even greater mold contamination concern.

Window air conditioner leaking into wall causing mold.

The photo above shows an air conditioner in the window of an older home with pillows filling the openings on the sides of the air conditioner. The peeling paint on the windowsill is evidence of both drain pan and rainwater entering the wall system below resulting in a much larger mold concern.

DIY Mold Inspection

If you see visible mold and mildew, detect a musty smell, or have any mold symptoms that could be related to your home, read the Do-It-Yourself Mold Inspection series from

Book cover for DIY Mold Inspection

In this series you will learn how to perform your own mold inspection without the cost of hiring a mold remediation company, spending money on mold testing, or risking a common mold scam.

I’ll walk you through every room in your home, including the attic, garage, and basement/crawlspace. Using inspection photos with explanations, I’ll show you why and where to inspect for mold, and how to see hidden mold when it’s the same or similar colors as the surfaces it grows on.

Once you learn the methods of proper mold inspection, you’ll likely be surprised to see how much mold is actively affecting your indoor air quality and putting you at risk of mold symptoms. Typically, whenever mold is discovered in one location, you’ll find black mold, white mold, and other colors of mold growing in additional locations.

Don’t waste your money on mold testing

I often get calls from clients wanting me to do black mold testing, In good conscience, I try to talk people out of paying me to do this work.

Microscope for mold testing

Mold testing is largely a waste of money. Knowing the species of molds you have in your home is basically useless information. Your goal should be to find ALL areas of mold growth and safely eliminate them from your indoor environment.

Similarly, while air filters and air purifiers can significantly improve indoor air quality in mold-contaminated homes, they are NOT a substitute for a mold inspection.

You could easily spend hundreds (or thousands) of dollars purchasing products, testing for mold, or hiring professionals to look at your home, and still risk becoming a victim of incorrect information or buying devices that will not solve your problems. Wouldn’t you rather have expert information from easy-to-read books that are only $7.99?

Mold Remediation

Whenever mold is discovered, before proceeding with DIY mold remediation or hiring a professional mold removal company, the responsible thing to do is to become familiar with proper and improper methods of mold cleaning. You can do this by reading the book Do-It-Yourself Mold Cleaning and Prevention.

Book cover for DIY Mold Cleaning and Prevention

In this book I’ll teach you how to:

  • make your own mold remover solutions
  • protect yourself from mold exposure while performing mold removal
  • prevent mold spores from spreading further around your home
  • avoid being scammed by mold companies should you wish to hire one
  • prevent mold from returning


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Would you like to learn more right away…for free?

Download your complimentary copy of one of the most helpful books you’ll ever read on indoor air quality by clicking this link: 6 Steps to Healthy Indoor Air.

Steps for Healthy Indoor Air

This book is my gift to everyone who wants to prevent or is already suffering from, allergy symptoms, asthma symptoms, headaches, migraines, ADD, ADHD, sinus infection, ear infection, memory loss, Alzheimer’s disease, insomnia, and cancer.

This is not a ho-hum book. It’s based on over 30 years of home investigations and includes photos with detailed explanations to help you learn the right way to protect yourself, avoid medications with side effects, and not waste money on air filters or air purifiers that are not as efficient as implied.

In 6 Steps to Healthy Indoor Air, I will teach you actual causes of and practical solutions for poor indoor air quality. And because I offer this as a free book, I want you to feel comfortable sharing it with others you care about.

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