Should You Worry About Mold in Your Air Conditioner?

As the temperature heats up, the possibility of mold lurking in your air conditioner can be cause for concern.

If you’re worried about mold in your AC unit, you can take steps to prevent its growth. If you find it already lurking in dark crevices, be sure to follow safe cleanup procedures. And if you have any unexplained symptoms, it’s best to check in with a doctor.

Why Does Mold Grow on Air Conditioners?

Air conditioner mold growth may be inevitable in some parts of the United States where the climate is often hot and humid, says Jordan Peccia, PhD, a professor of chemical and environmental engineering at Yale University in New Haven, Connecticut.

“In humid areas like the eastern U.S., a lot of water will condense on the air-conditioning unit’s cooling coils and potentially get onto other components like the fans, so that’s where one would have the highest risk for mold growth,” says Dr. Peccia, an expert in molecular environmental biology who’s conducted research on fungal and bacterial growth on air-conditioning units.

How Can You Tell if There’s Mold in Your Air Conditioner?

• Discolored, fuzzy-looking, or slimy patches on a surface area
• Water staining or warping damage
• Musty odor

How Does Mold Make You Sick?

• Itchy, irritated, or watery eyes
• Runny nose
• Nasal congestion
• Headache
• Sneezing
• Itchy skin, particularly around the nose, mouth, and lips
• Rashes
• Dizziness

Check with a doctor if you have any of these symptoms without any obvious cause, especially if they’re getting worse or have lasted for a long time.

How to Clean Mold From Your AC Unit

If mold is growing in your air conditioner, it’s important to clean it up and fix the moisture issue so the mold doesn’t grow back.

• Scrub clean and dry completely. Use a mixture of soap and water to wipe the affected surfaces, then ensure they’re dried completely.
• Check the AC unit’s manufacturer instructions. Depending on where the mold is located, keep in mind that you may need to safely disassemble some of the unit’s pieces according to the instruction manual or consult a specialist.
• Protect yourself from additional exposure. Wear gloves, a mask, and goggles while cleaning to limit your exposure to mold. And check with a healthcare professional first if you have asthma or another underlying health condition that compromises your immune system.

Can You Prevent Mold From Growing Inside Your AC?

“The easiest way to keep your home air-conditioning unit free of mold growth is to drain away the water as much as you can and install a better filter,” says Peccia. Better drainage will help keep the inside of the AC unit drier, he says, which prevents a moldy environment.

• Keep up with filter maintenance. Replace air conditioner filters according to the manufacturer’s recommendations — typically every 60 to 90 days.
• Control humidity. Maintain indoor humidity levels below 60 percent, and use a dehumidifier if needed.
• Stay dust-free. Keep your home and space around the air conditioner dusted, and try an air purifier to remove excess particles and microbes from the area.
• Consider upgrading. Check the efficiency of your air conditioner’s air intake filter and upgrade to a higher-quality filter if needed. With a better filter, excess dust gets trapped and won’t be able to feed mold growth in the air conditioner — even if there is some moisture present, Peccia notes.

The Takeaway

• All air conditioners are prone to mold growth because they provide the moisture, warmth, and dust that mold needs to thrive, especially in humid climates.
• Mold can often be identified by its fuzzy, slimy appearance or a musty odor.
• Mold exposure can cause symptoms like congestion, coughing, sneezing, and skin rashes, with more severe reactions possible for people with mold allergies, asthma, or compromised immune systems.
• Follow safety tips when cleaning up mold. For prevention, keep your air conditioner clean and dry, and replace filters regularly to help prevent AC unit mold growth.