Dirty Sock Syndrome and How to Fix It

dirty ac system close up

If you smell something funky in your house and have checked the garbage, laundry, and under the kids’ beds, you might wonder what’s making it smell. Believe it or not, the funky smell could be coming from your HVAC system, and it even has a name – Dirty Sock Syndrome.

DSS happens when the evaporator coil accumulates dirt, mold, and other microbial organisms. Fortunately, it’s not a cause for immediate concern, but you must put up with the smell until you have it fixed.

However, if mold is the culprit, your family’s health could be at risk because the spores could enter your home. This is most problematic for anyone with chronic health issues or allergies, but it’s not good for anyone to breathe in mold.

In this article, we’ll help you understand Dirty Sock Syndrome, why it happens, and what you can do about it.

Table of Contents

Understanding Dirty Sock Syndrome

If you have DSS, it means you have harmful bacteria or mold on your evaporator coil. Since the HVAC system pushes air into your house, if you have DSS, chances are it’s not clean air.

So why does this happen?

Don’t worry! This doesn’t mean you are dirty or your home is dangerous. It’s just that the HVAC system is in the right place at the right time for mold and bacteria growth. Here’s what happens.

Your HVAC system naturally has moisture in order to heat and cool the air. However, there’s one problem. Because you likely use your HVAC system in short spurts, the moisture sits, and if it’s in a dark, damp area, it can quickly turn to mold spores or bacteria. Plus, sitting idle gives the system more time to accumulate more dirt, dust, and debris.

What are the Risks of DSS?

Dirty Sock Syndrome can be harmful to your household members and your house. It’s not usually a life-threatening issue, but it can make some people uncomfortable and put those with serious health issues at risk for respiratory issues.

In household members, DSS can cause itchy eyes, a scratchy throat, fatigue, and headaches. It can also create breathing problems or worsen an already challenging respiratory issue.

The problems with your HVAC system can be really severe. Dirt and debris buildup reduces air flow, puts more stress on your HVAC system, and causes premature failure.

Eventually, it can lead to higher utility bills, more frequent HVAC repairs, and eventual system replacement.

How to Fix Dirty Sock Syndrome

Dirty Sock Syndrome isn’t just a bad smell that can go away; it can cause physical harm to your family, so you must know how to fix it. It’s usually best to leave the job to a professional.

The good news is that it isn’t an expensive repair. While calling for professional services is the key to properly handling the issue, it’s not an emergency or something that will destroy your budget.

If you call immediately and resolve the problem quickly, the HVAC contractor can likely clean the evaporator coil, and you’ll be back in business. However, if you wait too long or don’t realize there is an issue, you may need evaporator coil replacement. Fortunately, this part is often under manufacturer warranty, so you may get the part for free.

You can also attempt to clean the evaporator coil yourself; however, beware that you might void the manufacturer’s warranty by doing this. If the buildup isn’t severe, consider these steps:

  • Turn off the power to the air conditioning unit
  • Open the access panel to the Indoor air handler unit
  • Use compressed air or a no-rinse evaporator coil cleaner, depending on the manufacturer’s instructions

If you decide to  wait for a professional to be available to come to your house, here are some temporary fixes:

Change the Air Filter

The air filter traps dirt, debris, and contaminants, including pet dander, human skin, and other cells floating through the air. A buildup of these particles can reduce airflow and prevent the HVAC system from removing moisture from the air. When the air filter becomes damp, mold and bacteria can grow.

Changing the air filter reduces the dirt, debris, and bacteria that travel through your HVAC system. To avoid this problem, change your filters regularly and immediately if you smell dirty socks in the air. Most air filters require replacement every 30 – 90 days.

Clean the Evaporator Drain Pan

The evaporator drain pan collects condensation from the coils. If the pan has accumulated dirt and debris, mold and mildew can grow much more easily. If the pan is full of water, it’s probably clogged.

You can usually clean the drain pan yourself with hot water. If the drain hole is clogged, try poking it with a pin or paperclip. If you aren’t comfortable doing this, call an HVAC professional for help.

Use a Dehumidifier

A dehumidifier isn’t a solution to Dirty Sock Syndrome, but it can stop it from worsening or prevent it from happening in the first place. In an emergency, you could set up a portable dehumidifier to remove excess moisture from the air and prevent it from turning into mold. For a long term solution, you could have a whole-house dehumidifier installed to prevent DSS in the first place.

Preventing Dirty Sock Syndrome

Identifying and fixing Dirty Sock Syndrome is just the start of the process. Once you’ve experienced it once, you won’t want to go through it again. Fortunately, there are ways to prevent it from happening.

  • Regular HVAC maintenance: Keep up with your regular HVAC maintenance appointments, having your system checked twice a year. During the inspection, the professional can determine if the unit accumulates too much moisture and will clean the evaporator coil so you don’t have to deal with harmful fumes.
  • Check for proper drainage: If you notice any clogs or airflow issues, call for professional help immediately. If the air cannot flow properly or the moisture cannot drain, it can create a breeding ground for mold and mildew.
  • Get your ductwork cleaned: Dirt and debris originate in the ductwork. Regularly cleaning the ducts eliminates the risk of dust and debris accumulating and causing problems.
  • Upgrade your air filter: A high-performance air filter may capture more particles of dust and debris that could lead to DSS. If your HVAC system allows it, consider switching to media filters to ensure you capture even the smallest particles.
  • Use a UV light: A proper UV light can kill mold and bacteria that cause smells in your HVAC system. While it can’t remove a smell that already exists, frequent use could prevent DSS from occurring in the first place.


Dirty Socks Syndrome isn’t something you’d ignore because the smell is usually pretty strong. The key to reducing the smell and preventing the problem is eliminating the risk of mold and mildew growing in your HVAC system. The best way to prevent this problem is to have regular maintenance checks, change the filter, check for clogs, and clean the air ducts.

If you’re looking for an HVAC professional to handle your DSS or to help you prevent it, find the perfect one!

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Is dirty sock syndrome harmful?

Dirty Sock Syndrome can put at-risk individuals in danger or make anyone susceptible to mold and bacteria uncomfortable. It can also put unnecessary stress on your HVAC system, causing unnecessary repairs or early replacement of the system.

What are dirty sock syndrome symptoms?

Dirty sock syndrome isn’t life-threatening, but it can cause problems for people who already suffer from medical issues. Even if you don’t have medical issues, the smell can be very strong and cause things like itchy skin or eyes, a scratchy throat, or trouble breathing.

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