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Premier Heating & Air Blog

What’s That Moldy Smell Coming From the AC?

Girl pinching her nose

Here’s an odor you don’t want floating around inside your house: a moldy stench that smells like a pile of dirty socks. It seems to be coming from the air conditioning vents. What’s causing it and what can you do about it?

It won’t shock you to learn that what you’re experiencing is a common problem with air conditioners known as “dirty sock syndrome.” Yes, the people who named it knew exactly what they were talking about. No, nobody has tossed a bunch of dirty socks into your HVAC system (I mean, we don’t think so). But the odor is coming from the same source as smelly socks—bacteria from microbes. You’ve got a source of it in your AC, and we can probably guess what it is. Below we’ll talk more about how dirty sock syndrome happens in an air conditioner and what you can do about it.

The Moldy AC Evaporator Coil

We bring up this topic now because spring is the season when this is most likely to affect your air conditioning. The reason is a combination of high humidity and less work for the AC. You won’t run your air conditioner as often in this time of year, and that allows more time for moisture as well as dust to start to build up inside the unit, primarily across the indoor evaporator coil. This coil is where the most moisture collects in the air conditioner. The damp environment makes it easy for mold, mildew, and bacteria to develop. As air moves through the HVAC system, it must pass by the coil, where it will pick up the unpleasant odor from these growths and spread them around the house.

The Bad News About a Moldy AC

What, aside from the odor? Yes, that’s definitely bad enough on its own. But this isn’t just a cosmetic problem—you don’t want mold and bacteria developing along your AC because of two other factors:

  • It will lower the efficiency of the AC. Any layer of grime over the evaporator coil makes it harder for the air conditioner to absorb heat through the coil. 
  • It can harm your indoor air quality. Dangerous mold can send toxic mold spores into the house that will trigger allergies and asthma in sensitive people. 

What to Do About Dirty Sock Syndrome

The easiest way to deal with dirty sock syndrome is to call us for air conditioning repair in Conyers, GA. It’s not just that you need us to clean the coils and the rest of the air conditioning system to remove all the mold, mildew, and bacteria. You also need us to find out why it started to develop in the first place.

Often, the reason for the spike in humidity inside the AC is due to a problem with the condensate drainage system. If the condensate drain is partially clogged or water is leaking from the condensate pan, it will increase the humidity inside the unit and lead to problems like this. You’ll want condensate problems fixed because they will eventually cause the entire air conditioning system to shut down. 

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