Mold in an air conditioner is a common problem since it has warm, moist areas that don’t get much light. Unfortunately, your air conditioner can become a prime target for mold growth if it is not properly maintained. Organic matter from airborne dust and dirt can build up in the filter, giving mold the material it needs to breed. Luckily, you can prevent mold from settling into your air conditioner by regularly cleaning or replacing the filter.
If your air conditioner hasn’t been used in several months or you keep smelling a musty scent when it’s turned on, inspecting it to determine if mold is growing in the unit is a good idea. Use this guide to learn common signs of mold growth, how to check for mold, and what to do if you find mold growing in an air conditioner.
Common Signs of Mold in Air Conditioners
Look for a few key signs to spot mold in your air conditioner. A musty smell when the AC is running is often the first clue. If you have a window-mounted or freestanding system, the smell from mildew will usually be contained within that room. However, if your central air conditioner is affected, that musty scent can spread throughout your entire home.
Visible mold is another clear indicator. Check for fuzzy patches in colors like black, green, or black-green. Though black mold is most common, mold can also appear in hues of brown, white, pink, yellow, or orange.
How to Check for Mold in Air Conditioners
If a lingering musty smell has tipped you off to mold in an air conditioner, the next step is to inspect it to verify that you have a mold problem. You can inspect a small window-mounted, freestanding, or wall-mounted unit by unplugging the unit and removing the front or back grille to access the filter.
Use a dehumidifier to reduce moisture, and place odor absorbers like activated charcoal or boiled lemon peels nearby to help eliminate musty smells from a moldy AC unit.
Pull the filter out and visually inspect it for brown, black, or greenish stains that might look fuzzy. If the filter doesn’t show any signs of mold, grab a flashlight and inspect the inside of the unit. Mildew can also produce a powdery gray or white residue.
If you have a central AC unit, this process is more difficult because the bulk of the appliance is largely inaccessible. You can use a flashlight to inspect the supply vents, air ducts, fan, and exterior AC unit for signs of mold buildup. You will need to hire a professional HVAC maintenance company for a more thorough inspection.
What to Do If You Have Mold in an Air Conditioner
Addressing mold in your air conditioner should be a priority. If you discover a heavy mold infestation in a small AC unit, it’s usually best to replace it. Even thorough cleaning might not reach all of the layers and nooks infiltrated by mold, thereby allowing mold to persist. Investing in a new unit can prevent further issues and maintain your home’s air quality.
Removing Mold Yourself
However, if the mold is relatively light, then you might be able to get rid of it before it spreads throughout the AC unit.
Wear gloves, safety glasses, and a face mask, then move the unit to a space where it can be cleaned without contaminating the rest of the home, such as the driveway. Open the air conditioner and remove the filter. You can either replace the old filter if it is disposable or wash it in a mix of 1 part liquid bleach to 10 parts water,1 allowing it to soak for at least 10 minutes to kill any mold.
Rinse the filter and allow it to air dry. While the filter dries, deep-clean all affected surfaces of the air conditioner with the solution of bleach and water. Rinse off the AC unit, being careful not to soak any electrical components, and allow it to dry before reinstalling the filter.
When to Contact a Professional
Dealing with a minor mold infestation in a window-mounted, freestanding, or wall-mounted AC unit is typically manageable for a DIYer, but if you have a central air conditioning system, it’s recommended to call a professional HVAC maintenance service. Trained professionals who deal with these situations regularly can gain access to all affected parts of the system and treat the problem directly without damaging the central AC, air ducts, or vents.
In some cases, it might be beneficial to look for an HVAC company that contracts yearly maintenance so that you know the system is always clean and up to date. This also saves you the trouble of tackling maintenance projects, like changing the furnace filter or cleaning the air ducts.
How to Prevent Mold in an Air Conditioner
Beyond professional maintenance, you can take steps to help prevent mold growth in your home and in your AC unit. One method is to reduce moisture buildup in the AC unit by regularly emptying the collection reservoir or investing in an air conditioner with humidity control.
You can also prevent mold growth by cleaning the unit at least once a week and checking the filter.
Replace disposable filters about once a month or as recommended by the manufacturer. If you have a reusable filter, make sure to clean it once a month.
Additionally, running the air conditioner can reduce mold buildup because the constant flow of air prevents mold spores from settling on the surface. If you don’t want your air conditioner running constantly, increase the temperature instead of turning it off completely. This will allow the AC to turn on intermittently, reducing the chance of mold settling inside the machine.
