Dirty Sock Syndrome: Things You Need to Know

We expect an air conditioner to provide efficient cooling in a room, making us feel comfortable. Nonetheless, there are also instances wherein the AC may lead to discomfort. One of these instances would be when the unit is blowing air with foul smell, which is also known as Dirty Sock Syndrome. Read the rest of this post and you will learn more about the latter.

Dirty Sock Syndrome

What is Dirty Sock Syndrome?

In the simplest sense, Dirty Sock Syndrome refers to a situation wherein your AC blows air with an unpleasant smell, which will remind you of dirty socks. The main cause of this foul smell is the presence of mold and bacteria in the coils. The latter is due to the presence of moisture, which becomes worse when it combines with airborne organic debris and dirt.

This is a problem with indoor air quality. Because it is caused by the build-up of bacteria, a lot of you may be worried if it is indeed dangerous. In most instances, it is harmless. It should not be a significant health concern. Rather, all that it can cause is discomfort on your end. You might have difficulty sleeping because of the smell that is emitted by the AC.

When does it become dangerous? It becomes a more significant concern when there is a presence of mold. According to experts, most types of molds are only mildly toxic when humans are exposed. Bacteria can grow into a mold, which makes it important to address the problem as soon as possible before it becomes more serious.

In worst cases, the mold can lead to eye irritation and difficulty breathing, especially for people who have existing health problems. It can also result in nausea because of the smell that some people might find hard to bear.

How to Prevent Dirty Sock Syndrome?

As they say, prevention is better than cure. That being said, before we discuss some of the best ways to treat the problem, let us first have a quick look at how it can be prevented in the first place.

One of the best things that you need to do is the regular cleaning of the evaporator coil, which is where the bacteria and mildew can accumulate. The evaporator coil is a critical component of the cooling system, which is why you might want to leave the job in the hands of the pros to be sure that they will be able to do it right.

Regular emptying of the drainage pans will also help to prevent this problem. If you remove the water that pools in the pan, there is a lesser likelihood that there will be a growth of bacteria. It will also provide you an indication if the drain of the AC is properly working.

It will also coat the coil with an anti-microbial agent. The latter will provide a protective coating that will make it less likely that bacteria will grow and cause a foul smell when you are using your AC.

How to Fix Dirty Sock Syndrome?

Sometimes, it is too late before you can act to prevent the problem. In this case, you have to think of how to have it fixed when prevention is no longer enough.

The best thing that you can do to fix the problem is to clean the evaporator coil, which is the main source of the problem. For your safety, make sure that the unit is turned off. Prepare the cleaning solution, which should be a combination of three parts water and one part bleach. Look for the evaporator coil and clean it using the solution that you have prepared. Use a brush and allow multiple passes of the cleaning solution.

If the coil can no longer be cleaned, which can be a result of wear and tear through many years of use, it would be better to just have it replaced.

If you are unsure of what to do, the best thing that can be done is to ask help from HVAC professionals. They have the tools and the expertise that will be needed to fix the problem.


In sum, Dirty Sock Syndrome happens when your AC is working and blowing cool air, but there is a noticeable foul smell. This can be a nuisance, especially in the bedroom. The problem is caused by the build-up of bacteria and mildew, which can also develop into a mold. Make sure to act as soon as possible to remedy the problem and prevent it from having negative impacts on your health.

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