This issue has been coming up more and more of late! The thing you first have to understand is how your a/c system works. Not only does the a/c system cool the air that supplies your home, but it also removes the humidity from the air. When an HVAC Specialist comes and inspects your system, he will look at and inspect the coils, this is where air is moved across to cool it, and what ever moisture is in the air gets separated and will drop down into the drain pan. An HVAC Specialist will tell you, or, should tell you to put bleach periodically in your drain pan so that slime does not build up and stop up the drain line. If you don’t do this, you may regret it if the drain pan overflows and starts dripping out the ceiling, this can run into a large repair bill.
Now that we know how moisture is in your system, understand that this moisture will travel through your ducts and collect on the walls of the ducts in the way of condensation, remember what happens when cool air meets warm ducts!
So, how do I know if I have any mold or mildew in my a/c system? There are many indications that will help you determine if your system is contaminated with the mold spores, first off, if you or your family members have breathing problems or allergies that you can’t determine what it is from, there could be mold or mildew in your system, if you smell something moldy and can’t determine where it is coming from, it could be in your system. If you remove a few of your a/c duct grills and visually inspect your system, you could very well see the mold or mildew growing, and once it starts, you need to have your system treated to stop and kill any mold or mildew from growing.
There are a couple of ways to attack this problem, one is when you are having your system inspected by an HVAC Technician, have him clean your cooling coils, even though you change you’re a/c filter periodically, there can be dirt build up or mold and mildew on you coils, one thing to remember is that every time you open your door or window, humidity and dirt can enter your home and get sucked into the system. The everyday filter that most people buy at the store only stops so much, the HEPA filter are the best, but they cost a lot more, but they are worth it when it comes to the health of your house hold. If the mold and mildew is discovered on your cooling coils, you can bet that it is inside your ducts as well. Another way to kill the mold is by have your system treated, this is where they will fog you a/c ducts with a disinfectant that is designed to kill the mold and mildew growth. Some the disinfectant on the market will kill 99.9% of any bacteria or mold and mildew in the system. You have to have a complete and thorough fogging/treatment in the system, that means starting at the plenum (the air supply box), cleaning and fogging each individual supply duct coming out of the box, and then go to each supply grill and fog from there as well, this way you know that you have completely saturated the system.
There is one other thing that you can do to control and kill any bacteria in your system and that is by installing U/V lighting in your a/c plenum and sometime on the intake side of the a/c unit. The u/v light has been used in several instants in the past in the medical field when it comes to fighting bacteria. Just in the last several years have HVAC companies started installing them in the residual systems. At one time when I worked in the maintenance department for a large property management company, we started having the u/v lights installed in the air handler units, they were 10 ton units, and this was to kill and control the mold and mildew from getting into the system, this helped with air quality control.
There are plenty of articles that will tell you more about U/V lighting, but this will help you get started in learning what to do to fight mold and mildew in your system or to prevent it from getting started in your system.
I hope this article has been helpful!