Mold In Air Conditioner: Causes And Signs

Mold in your air conditioner (AC) is bad news for three main reasons. First, mold can cause respiratory illnesses in your household. Secondly, mold can cause structural damage. Lastly, mold is a sign of a deeper problem in the house. Below are some causes and signs of AC mold.


Mold thrives on wet organic matter. Below are things and circumstances that encourage AC mold.

Water Leaks

The AC extracts moisture from the air as part of its cooling process. The extracted water condenses and drains out of the system. AC malfunctions or damages, such as holes in the condensate drain line, allow moisture to leak within the system. Such moisture encourages mold growth.

High Humidity

Your AC might fail to lower your house's humidity to safe levels if your house's humidity is too high, to begin with. The high humidity will encourage mold growth in all parts of the house, including the AC.

Dirt and Debris

Organic dirt and debris provide the perfect medium for mold growth. Dirt and debris can clog the AC if you don't clean it or replace the air filter regularly enough.

Poor Airflow

Poor airflow allows dirt to gather on some parts of the AC. Poor airflow also allows humid air to collect within the AC. A clogged air filter can create both circumstances, which encourage mold growth.


Know the signs and symptoms of AC mold so you can deal with the problem before it's too late. Below are some signs to watch out for.

Musty Odor

Mold has a distinctive musty smell that many people recognize. Some people describe the smell as old or decayed. You should suspect mold growth when you sense such smells near the AC.

Respiratory Problems

You should suspect mold in your house if members of your household start experiencing respiratory or allergic problems. Class symptoms include coughing, wheezing, congestion, and sore throat.

Visible Stains

You might also notice mold signs on the AC and nearby surfaces. Mold typically appears as black or dark brown patches. However, you should suspect any unusual stains on the AC.

Poor AC Performance

Extreme mold growth can also affect the AC's performance. For example, the mold can restrict airflow, which is central to the AC's cooling efficiency.

Contact a contractor if you suspect mold on your AC system. The contractor will deep clean the AC to get rid of the mold. The contractor will also diagnose the cause of the mold and deal with it to prevent a reoccurrence. 

Speak to a service provider to learn more about your AC unit.