Penpak Ngamsathain/
Who among us isn’t cranking up the air conditioning to a face-blasting level during these sweltering summer months? However, you might be unknowingly inhaling a whole lot more than just cool air—mold, allergens, and other unsavory nasties. Although Midea air conditioners were recalled earlier this year due to the risk of mold development, they’re far from the only AC units susceptible to fostering mold or spreading contaminants within your home. Given their function—removing moisture from the air while cooling—it’s a fact that every air conditioner or HVAC system has the potential to harbor harmful microorganisms.
Michael Rubino, a mold and air quality specialist and the founder of HomeCleanse, points out, “Mold in air conditioners is quite common if they’re not maintained properly.” So, if you’ve neglected your AC unit, here’s why you should take a closer look—and what to do if you find something less than appealing growing within it.
Michael Rubino is a mold and air quality expert, the founder of HomeCleanse, host of the “Never Been Sicker” podcast, and chair of the Change the Air Foundation.
Just about anything that can enter the air or land on surfaces can be drawn into and expelled from your air conditioner. Organic materials, in particular, can easily flourish and grow within the unit. “Moisture and organic matter are the two main ingredients for microbial growth,” Rubino explains. Pet dander, mold spores, bacteria, or any other organic debris can thrive on the AC coils, where condensation forms as the cold coils cool the air and expel moisture.
“The tricky part is that it may take some time before you notice it, as the coils are typically out of sight,” Rubino adds.
Window air conditioners are most prone to contamination, Rubino notes. They often sit unused for extended periods, suffer from drainage problems, may not be installed correctly, and are not always cleaned as frequently as they should be.
There are several warning signs that might indicate your air conditioner is causing problems.
You may notice the mold growth when you open your AC unit or inspect the filter. “Mold can appear in a range of colors, from white to green, blue, pink, grey, black, brown, and more,” Rubino says. “It can also have different textures, like powdery, slimy, or fuzzy.”
You might detect an odor before you see the mold. “Mold doesn’t always present itself visually, but it often emits a distinctive smell,” Rubino says. “It releases gases known as microbial volatile organic compounds (MVOCs), which create that familiar musty, damp, or earthy odor.”
Exposure to these types of microorganisms can lead to various symptoms, including brain fog, fatigue, congestion, coughing, and headaches, according to Rubino. “If these symptoms seem to worsen when you’re at home, it’s worth looking into further.”
Mold may be discovered when an HVAC professional services or inspects your unit, or you can test the dust in your home to check for mold or other contaminants.
If you’ve had mold issues in your home before, you know it’s a challenge to clean thoroughly. If it’s a window AC unit, Rubino suggests disposing of it. “Cleaning can be attempted, but it’s not guaranteed that all particles will be removed, which can lead to prolonged exposure or a recurrence of mold growth.” You’ll want to decontaminate the area where the air conditioner was and replace it with a new unit.
For minor mold contamination in a window air conditioner, you can remove it from the window and clean it outside. Clean the grille and filters, use an anti-mold cleaner on the coils, and let the unit dry for 24 hours before reinstalling it, ensuring it’s properly installed to release moisture outside.
For mini splits or central air conditioners, Rubino advises calling an HVAC professional to assess the situation and perform a thorough cleaning. “A professional can inspect internal parts like the evaporator coil and drain pan, test for moisture buildup, and determine if microbial growth is present. Their findings can guide whether remediation or more extensive action is needed.”
If mold can be effectively cleaned, a professional is your best choice for removal. “Coils can be difficult to clean due to the tiny gaps between the fins, so it’s always wise to seek a professional opinion,” Rubino advises.
While proper AC maintenance may not prevent contamination entirely, it can help you identify and address issues more quickly. “Regular inspections can help spot problems early so they can be addressed, whether it’s moisture or active microbial growth,” Rubino says. You should clean and inspect filters weekly to help remove organic material before it becomes a problem.
