What is HVAC Dirty Sock Syndrome?

Photo of a person taking out an HVAC filter. HVAC Dirty Sock Syndrome

Does your home smell like a dym after soccer practice? It could be HVAC dirty sock syndrome! Learn about what it is and how to get rid of it below.

This common problem happens when your HVAC unit has built-up moisture, dirt, dust, and other household elements that find a home in your evaporator coil and then multiply. The stronger the scent, the more severe the problem. HVAC dirty sock syndrome gets its name due to smelling like moist, bacteria-rich dirty, smelly socks! You can avoid it and treat it to keep your home’s air healthy and smelling fresh.

What is HVAC dirty sock syndrome?

This is a common problem with modern homeowners that have HVAC units. It’s so common that it has earned its name of dirty sock syndrome (DSS for short).

This condition is where an HVAC unit’s evaporator coil collects moisture, dirt, debris, and more build-up. When your unit turns off, the collection settles on the coil in the moist environment mold, and bacteria grow in these conditions. When the coil starts back up again, the mold scent is blasted through your ductwork.

Despite what the name implies, there is no need for literal dirty socks in your home to cause this condition. It’s due mainly to improper unit care (by yourself and/or an HVAC technician). I’ll talk about that next.

Causes of HVAC dirty sock syndrome

Now that you understand how DSS got its name and what it is, let’s take a moment to dive deep into the causes. Understanding where DSS comes from will be integral to preventing and/or treating it in your home! The top causes include:

  • Neglect of regular maintenance
  • Improper maintenance
  • Having too much moisture in the home

Neglect of regular maintenance

You know how your care manual explains the need to clean the air filters and keep the unit clean from dust and pet hair? That’s all for a reason! It ensures that your unit and its filters don’t let in any mold or build-up to the evaporator coil. The closer you follow the recommended instructions in your care manual, the better you’ll prevent your unit from developing DSS!

Improper maintenance

You’ll need to have an HVAC technician survey your unit every once in a while. They’ll check for potential coil issues, the unit’s overall function, and so on. If they are coming at their regular intervals, they should be experienced enough to understand when your unit needs a bit of care to keep it working its best.

Hiring a professional, licensed, and recommended HVAC technician is crucial to ensuring your unit gets the best care possible. If a technician misses a sign of wear and tear, it could lead to DSS in your unit, even if you are doing all you can to care for it.

Having too much moisture in the home

DSS can’t develop without moisture, and most homes have a lot of it. Whether it’s due to your HVAC base unit is mounted in the basement or just the general climate you live in, environmental humidity creates the perfect conditions for DSS. This, coupled with the hard-working evaporator coil, create a breeding ground for mold. 

Is dirty sock syndrome harmful?

So far, DSS sounds gross, but what about its actual impact on our lives? Is dirty sock syndrome dangerous? For most people, it is just gross and mildly irritating. Some people may notice irritation in the nose, throat, and eyes. Those with more severe DSS cases will notice headaches, fatigue, and achiness, and even a stronger chance of getting sick!

The real danger of DSS is in the immunocompromised or those with asthma. Asthma is common in children at a 6% rate — much higher than it was back in the day. Since childhood asthma can impact adulthood life and provoke a weakness for respiratory-based illnesses lifelong, this is essential!

Does dirty sock syndrome go away?

Dirty sock syndrome is not a permanent thing that you have to live with if you’ve detected it in your home. You can treat it and then work hard to keep your unit safe from getting it again. However, ignoring it and simply turning off your unit won’t do. You must seek professional treatment for DSS or, at the very least, try a DIY option.

Is dirty sock syndrome mold?

If it’s caught in its earliest stages, DSS doesn’t necessarily guarantee that mold is being pushed out of your unit and into your home via ductwork. But you will deal with bacteria and mold if you leave it untreated. The earlier you detect an issue, the better your chances of keeping those mold spores out of your ductwork and out of your home!

Is dirty sock syndrome covered by warranty?

If you have a warranty in place with your HVAC unit that you haven’t voided or violated, then you’ll be happy to know that that warranty will cover DSS and its repairs/replacements. Even if you aren’t, though, the cost of fixing it isn’t extremely high, and it’s definitely worth your and your home’s health to treat it even if your warranty has expired!

How to prevent and treat HVAC dirty sock syndrome

Now for the important part, right? Let’s look at how you can keep your HVAC safe from DSS, preventatively or after the fact!

Preventative care:

  • Check and clean your air filters as recommended
  • Clean your evaporated drain pan
  • Schedule regular professional HVAC maintenance

After diagnosing DSS:

  • Have a professional assessment done of your HVAC
  • Deep-clean or replace your impacted evaporator coil
  • Have your ductwork cleaned professionally

TIP: You can upgrade to a high-quality air filter either preventatively or after the fact for better protection of your HVAC.

How do you fix dirty sock syndrome in an HVAC?

If you want to try to tackle the DSS yourself, there are a few DIY options that you can try out. Just ensure that doing these doesn’t void any warranty for your HVAC unit. Some policies allow for maintenance or repairs to be done only by a specifically licensed HVAC technician! DIY options include:

  • Making a vinegar spray
  • Making a bleach spray
  • Using a dirty sock syndrome spray
  • Investing in a dehumidifier 

Making a vinegar spray

This is a great natural choice to help disinfect and free your evaporator coil from the build-up you’re noticing. You’ll have to let the spray sit for a while so that it can do its work. You’ll also want to thoroughly clean the built-up mess and vinegar off your coil before turning it back on again.

Making a bleach spray

You’ll follow the same instructions as the vinegar for this option, but use Your Modern Family’s description of 1:8 parts bleach and water mix. This is great for those severe methods and those who want to kill the bacteria and the mold spores to keep any DSS symptoms from returning.

While it’s still not a replacement for proper preventative care after thoroughly cleaning and disinfecting your HVAC unit, this does help you start from a clean slate without replacing your evaporator coil.

Using a dirty sock syndrome spray

You can buy purpose-designed DSS sprays at stores or via your technician. These work faster and easier for your evaporated coil because they’re purpose-designed. These sprays are great choices if you have a common issue with DSS or just want to keep the work to a minimum.

Investing in a dehumidifier

If you seem to have chronic DSS or live in a particularly humid climate, you’ll find that investing in and using a humidifier will be an excellent idea. Not only will it help make your house more comfortable, but it also will keep your unit clean and clear from DSS.

When to call an HVAC technician for help

If you ever feel that you’re getting over your head in understanding how to care for your HVAC unit or even treating DSS, calling in the pros is a good idea. It’ll save you money in the long run, as counterintuitive as it seems. Bob Villa explains having proper care by proper professionals helps reduce the lifespan of your unit and keeps those repair costs low for as long as possible.

It could be dirty sock syndrome if you have an HVAC unit that doesn’t smell right. This happens when your HVAC unit has built-up moisture, dirt, and dust that settles onto your unit’s evaporator coil.

If left long enough, it can cause mold to grow, and that mold (as well as bacteria and general dirt) will be vented back into your home through your ductwork. The grime can find a home in your evaporator coil and then multiply. You can try both DIY and outsourced options. Just know when to call in professional help!

Know someone with this stinky situation? Share this with them and help them find their way back to a fresh home!

Rosa Peterson

Rose is the writer and creator of Better That Home, a blog about home design and decor. Rose has been designing spaces for over 10 years and writing home design and decor for big publishers. She has been inspired by many other creatives from around the world and loves to share those inspirations with her readers. Read more about Rose here