If you should notice an odd musty odor coming from your air vents or should you notice that the vents are becoming discolored the problem is likely the growth of mold. This is not unusual and there are a number of reasons why it happens.
During the summer the air is not only hot, it also tends to have high moisture content. As the air conditioner cools the air it also draws the moisture from it where ideally, it is drained off. If the air conditioning unit is inefficient, and older units often are, they cannot remove enough moisture from the air, the result is that excess moisture is delivered throughout the home, not only does this mean the rooms are damp and uncomfortable it also means the interior of the ducting is wet, when combined with dust this is a perfect environment for mold in air ducts to form.
When the air conditioner is not well maintained the coil can quickly become a magnet for dust, dirt and debris. As mold requires both water and organic material to grow, the interior of the duct rapidly becomes home for a colony of mold. The most common mold found in air ducts is Cladosporium; this mold grows quickly, produces a huge quantity of spores and is the source for the musty odor in the home. Mold from this family can cause skin irritation, eye problems and makes the air very uncomfortable for those with allergies or asthma.
Preventing the growth of mold in air ducts:
The old saying, “An ounce of prevention is worth a pound of cure” most certainly applies to mold problems. If you can prevent the establishment of a mold colony it is far better than having to deal with removing it. The best way to approach the problem is to ensure that the ducts are kept free of dust and dirt. These materials contain traces of organic material, when this comes into contact with water you have created the perfect environment for mold to prosper. The best approach is to ensure that the filters are cleaned or replaced on a regular basis.
If you do have a problem with mold in air ducts it is always best to have it removed by professionals that have the right equipment such as HEPA vacuums and know how to do the job in a safe manner. Once the ducts are clean it is recommended that they be coated on the inside with a material that will inhibit any further growth of mold.