How to clean mold from your air conditioner safely

Yahoo

23-06-2025

It's easy to view an air conditioner as a set-it-and-forget-it appliance, but these workhorse machines require regular cleanings to lower the risk of mold buildup. But if you're like most people, you probably don't know how to clean mold from your air conditioner (or how to identify if it needs cleaning in the first place). With that in mind, here's how to check and clean your unit and how to prevent AC mold in your home in the first place.
There are a few reasons why mold can grow in air conditioners. For starters, "mold is present almost everywhere," Jamie Alan, an associate professor of pharmacology and toxicology at Michigan State University, tells Yahoo Life.
But air conditioners in particular create a mold-friendly environment that allows spores to thrive. "Mold is a common issue in AC units because the cooling process naturally creates moisture," Flores says. "When warm air passes over the evaporator coils, condensation forms."
If the moisture doesn't drain properly from your AC, or if the system stays humid due to poor ventilation or infrequent use, it creates an ideal environment for mold to grow, Flores says.
There are a few things that can happen with a moldy air conditioner. "Mold will reduce efficiency and can also circulate spores throughout the home, which can cause health issues like allergies or respiratory irritation," Flores says.
According to the American Academy of Allergy Asthma & Immunology (AAAAI), mold and mold spores are incredibly common — you're going to breathe some of them in from the air around you. That said, some people are allergic to mold — their immune systems are overly sensitive to specific types of spores, which can lead to more significant reactions from exposure. Common reactions include sneezing, watery eyes, runny nose and nasal congestion. While there are hundreds of types of molds, the AAAAI notes that the most common ones that cause allergic reactions are Alternaria, Aspergillus, Cladosporium and Penicillium.
As to what may happen if mold starts growing inside your AC, Alan says that really depends on the type of mold, as well as how your immune system typically responds to such spores. For instance, people who are immunocompromised or who have underlying respiratory issues are more prone to experience symptoms or health complications from mold exposure.
Additionally, aerosolization of mold is a bigger potential issue than mold growing on a random surface, especially for people who are prone to mold issues, Alan says. If you're chronically exposed to mold by something like your AC blowing spores around, you could develop chronic allergy symptoms or other health concerns. "Patients could have lung infections, which could look like a fever, cough and trouble breathing," Alan says.
Something else to consider: Certain types of molds, like black mold, can release toxins into the air that can make you sick, even if you don't have a mold allergy. "With things like black mold, there are more symptoms that patients may experience like fatigue, mood changes and brain fog," says Alan.
There is also a specific immune reaction to mold spores called hypersensitivity pneumonitis where your lungs become inflamed due to mold exposure. "It leads to a flu-like illness with fever and fatigue, in addition to respiratory symptoms," says Dr. Robert Laumbach, associate professor in the Department of Environmental and Occupational Health and Justice at the Rutgers School of Public Health. "Over time, this could lead to permanent lung damage, so we want to try to catch [it] early."
A key sign that mold in your home may be making you sick is if you find that you're having asthma- or allergy-like symptoms in your home that seem to get better after you leave for the day. "Symptoms usually occur with exposure and then may resolve within hours," says Laumbach. (However, he says that it can take longer for symptoms to clear up for some people, so this isn't always a given.)
Still, all of this doesn't mean you should panic if you happen to find mold in your AC — especially if you otherwise feel fine. "Not every type of mold causes health issues for humans," Alan points out.
There are a few warning signs to look out for. "One of the most noticeable signs is a musty or earthy smell when the system kicks on," Flores says. "It is usually the strongest near vents."
You may even spot mold on the vents or around the evaporator coils and drip pan, Flores says. "Unexplained moisture buildup around the unit or damp, stale air could also be red flags," he adds.
But you may simply be tipped off to the presence of mold in your AC by how you feel when the AC starts running — pay attention for any telltale allergy symptoms mentioned earlier, like sneezing, a runny nose or coughing.
While it's never a bad idea to call in the experts if cleaning your AC seems like an ordeal, in most cases, it's possible to tackle basic cleaning yourself. Flores offers these simple steps.
Flores recommends protecting yourself first. That means wearing gloves, a face mask and goggles. "Disturbing mold can release spores," he says. Failing to protect yourself can increase the likelihood of experiencing allergy symptoms or irritation.
While basic cleaning is fairly straightforward, it's important to familiarize yourself with your unit and to determine whether the company has specific suggestions for ongoing maintenance.
You don't want to be poking around with the electricity still running.
Removing these components allows you to clean in and around them more effectively, identifying any areas where mold may be growing.
"Small amounts of mold in accessible areas like vent covers or drip pans can sometimes be cleaned with a mixture of water and a mild detergent or a diluted bleach solution," Flores says. But as you remove these parts, "be careful not to damage components," he warns. (This is where consulting the owner's manual may come in handy!)
Giving your AC a chance to fully dry before turning it back on will reduce the chances for mold growth to return.
If you suspect that mold is in deeper areas of your air conditioner, like the coils or blower motor, Flores says it's best to use professional-grade equipment and antimicrobials. "That's where trained HVAC pros come in, as we can safely clean and sanitize all affected areas without spreading the mold further," he says.
Getting rid of mold from your AC unit is helpful, but it can come back again if you're not careful. As always, it's best to read the instruction manual for your unit and follow regular maintenance, as recommended. "Proper routine maintenance can address most of these issues before they become a problem for the home," says Sean Goddard, product manager of indoor air quality and coils at HVAC company Trane Technologies.
Beyond that, Goddard says it can be helpful to keep tabs on your indoor humidity. "Indoor humidity should be kept between 30% to 50% for comfort and to prevent mold," he says. "Mold tends to grow when indoor humidity is higher than this range."
If humidity is a big issue in your home, Goddard suggests investing in a dehumidifier to try to help lower those levels.
You may even want to consider using UV light, Goddard says. "UVC light installed over your coil and drain pan can prevent microbial growth and mold," he says.
Laumbach suggests wiping down the inside and outside of your air conditioner regularly to remove dust, and to regularly clean and change your filter. "Dust can be enough food for mold to grow," he says. "You want to keep those coils and the filter clean."
You may even want to consider using an additional air purifier with a HEPA filter, or seeing if your AC unit can use a HEPA filter to tamp down on mold spores circulating in your air, says Tony Abate, a certified mold inspector and vice president and chief technology officer at AtmosAir Solutions. (Check out our favorite air purifiers.)
The Environmental Protection Agency (EPA) also recommends keeping your air conditioning drip pans clean and the drain lines unobstructed and flowing properly.
Mold can be an issue in any air conditioner. Mold exposure can raise the risk of a range of health issues, from allergy symptoms to full-blown infections, making it important to stay on top of the spores in your home. Doing routine air conditioner maintenance and cleanings will help to lower the risk of mold issues happening in the first place.
Omero Flores, CEO of American AC & Heating in Harlingen, Texas
Jamie Alan, RPH, PharmD, PhD, associate professor of pharmacology and toxicology at Michigan State University
Robert Laumbach, MD, MPH, CIH, associate professor in the Department of Environmental and Occupational Health and Justice at the Rutgers School of Public Health
Sean Goddard, product manager of indoor air quality and coils at Trane Technologies
Tony Abate, a certified mold inspector and chief technology officer at AtmosAir Solutions
Our health content is for informational purposes only and is not intended as professional medical advice. Consult a medical professional on questions about your health.