Can Mold Grow in My Air Ducts?

Here in Birmingham, we contend with a lot of miserable summer weather. While some of us may never admit to feeling the least bit bothered, the truth of the matter is that it gets downright hot and sticky here. This combination of heat and moisture can lead to a big problem: mold.

Most of us hear about mold popping up under sinks or in bathrooms. Is it possible for mold to start growing in air conditioners as well? Read on to learn more about this issue.

Short Answer: Yes, But It Is Uncommon

It is possible for mold to start growing in the ducts of your air conditioner. However, it is not an overly common problem. True, we have more issues with it than some other parts of the country, but an air conditioner that is functioning properly should not create an attractive home for mold.

An air conditioner keeps your home dehumidified as well as cool. The dehumidification process takes place in the condenser unit, located outside your home. Moisture removed from the air goes into the drip pan, where it drains away. If not enough moisture is removed from the air, either due to extreme humidity or from a problem with the air conditioner itself, then it can condense on the sides of your ducts. If the temperature is right, it is possible for a suitable home for mold to form.

Warning Signs of Mold in Your Air Ducts

The first sign many people notice is a musty, moldy odor. If you do a thorough clean of your home and the smell is still there, it’s time to check your vents. Removing the covers and taking a quick look inside may confirm the issue, especially if you see mold or notice a stronger smell in that area. If the scent is stronger, but you can’t see the mold, then the growth is possibly further in the ducts.

Another sign of a mold issue is the sudden onset of allergy symptoms. If you or a member of your household notices burning eyes, scratchy throat, or a runny nose that gets better when you leave the house, there could be an issue. Check your filter first – if it needs to be changed, install a new one. If the symptoms continue, do a quick check of your vents and a visual check of your ducts.

Inspecting your ductwork can also provide clues to a possible mold problem. Look for signs of moisture build-up, such as condensation, dark spots, or actual leaks. Mold needs water to grow, so any signs of condensation or leaking could indicate a growth hot spot.

What to Do if You Have Mold Issues

First, don’t panic. Mold in an air conditioning system is not overly common, but it isn’t unheard of. The problem can be fixed, but the severity of the situation needs to be established before a plan of action is put into place.

Some homeowners just do a quick clean-up of any mold or mildew they find right around their air conditioner vents. If mold is genuinely an issue, though, it is likely that it is growing further into the duct work and requires a thorough cleaning. Because some types of mold can be dangerous, we highly recommend calling a professional to inspect the HVAC system. An expert technician will be able to assess the entire system and determine the course of action needed. Usually, all that is required is a thorough cleaning of the ductwork and an inspection of the air conditioner to confirm that it is running properly.

Sometimes, though, the creation of a mold-friendly environment is due to a more significant problem. This can include anything from a part that needs to be replaced to an air conditioner that is the wrong size for your home. Again, if this is the case, don’t panic. A good technician will be able to explain the situation thoroughly and help to find a solution that will work for you and your family.


The Bottom Line: It is uncommon, but mold can begin to grow in air conditioning ductwork. If this happens in your home, see if you can find the problem area and call a technician. They will be able to assess the issue and find common-sense solutions that keep your air quality high and your home cool.