Why Does The AC Smell

Why Does The AC Smell?

Spring is the time of year when many of our air conditioners are switching back and fourth between heat and cool. When this occurs we can get a musty gym socks kind of smell from the units known in the HVAC industry as “Dirty Sock Syndrome”. Usually, this phenomenon occurs only in Heat Pump type air conditioners. This can be caused by a couple of things but usually is due to excessive moisture content and correct temperatures creating a perfect habitat for microbial growth in the air conditioner.

WAIT! Before you run out of your home thinking you have mold in your AC, remember that mold is only one of the types of microorganisms and that bacteria are just as common so mold might not actually be it. In Texas, our air conditioners work by pulling moisture out of the air making it dryer (think less humidity) and cooling the air in the process. This condensate as its called has to be carried away from the unit, outside through the drain lines or excess moisture can build up, and cause the musty smell we experience. So, cleaning out the drain pans and drain lines for our AC units can help prevent this odor.

Another culprit can be dirty evaporator coils. These coils are the ones inside the interior attic or closet part of the air conditioner and can build up dust and other contaminants from using poor quality air filter or not changing filters enough. These particles are food for microorganisms. So, cleaning the evaporator coils can also help. For this, only use soapy water, not acids as they can corrode the coils. After the coils are clean an antimicrobial spray such as Microban (a well-established brand) can be applied at regular intervals and allowed to dry on the coils to reduce microbial growth in the future. Bleach is not a good idea as it can corrode the coils and spread noxious fumes throughout the home.

If a frequent chemical application is not an appealing option or not working well enough an alternative is the installation and use of a UV-C Lamp inside the unit. These lamps emit UV-C, an odor free, sterilizing form of light naturally occurring in sunlight, into the unit completely destroying most of the microorganisms present. The main drawback of the lamps tends to be the cost of installation and the cost of new bulbs when they burn out.

The bottom line is that while dirty sock syndrome is annoying and obtrusive, it is a common problem and can be treated. If you need more info about dirty sock syndrome or how to treat it calling a licensed AC Tech is the best way to get info about your specific unit. If this is the case, we at Panther Inspections are connected to the top contractors in our area and have a referral for you!