How To Spare Your A/C System From Dirty Sock Syndrome

2 June 2016
 Categories: , Articles


Imagine turning on your air conditioner to beat the summer heat only to get a whiff of what smells like a dirty sock coming from your A/C vents. If the smell persists after putting away your dirty laundry, then chances are you're dealing with what's known as "dirty sock syndrome" -- it's when mold and mildew builds up inside your A/C system until it gives off a musty aroma.

Dirty sock syndrome isn't just annoying for your nose. It can also trigger serious allergy and asthma symptoms in children, the elderly and those who are just sensitive to mold and mildew. The following guide shows what causes these musty odors in your A/C system, as well as how to track down and remove the source of these odors from your unit.

Pinpointing the Source

Before you can tackle dirty sock syndrome with a vengeance, it's crucial to know how musty odors can develop in your A/C unit. Believe it or not, there are several possible answers to how the problem occurred in the first place:

  • Mold and mildew growth on or near the evaporator coil and the condensation drip tray can easily produce musty odors.
  • Stagnant water caused by a blockage in the drip tray drain can also produce unpleasant odors.
  • Mold and mildew growing in the ducts and vents can also cause musty odors.
  • An unchanged air filter can easily become the focal point of dirty sock syndrome, especially if the filter becomes damp or wet.

Even your home's current humidity level can play a role in creating those musty odors. Abnormally high humidity levels can easily promote mold and mildew growth throughout your home. Ordinary household activities such as cooking and showering can add heavy amounts of moisture to indoor air. Combined with poor ventilation, these activities can create a humid environment where mold thrives.

Tackling the Problem

The very first step you should take is to check the air filter located behind the central A/C system's return air vent. Check the air filter to make sure it's not damp or wet -- a wet filter could also mean the condensate drip tray has overflowed and also needs attention. If the filter is wet, use a flashlight to trace the water leak back to its source. If the filter is dry but caked with debris and dust, replace the filter with a new one.

The next step involves looking inside the A/C unit itself. Locate and open the plenum to gain access to the evaporator coil and condensate drip tray. Carefully check the evaporator coil and the surrounding areas for any signs of mold or mildew growth. If you see any, apply a foaming no-rinse spray to the evaporator coil or use mild soap and a soft brush to remove the mold or mildew growth.

Vacuum all of the standing water out of the condensate drip tray using a wet/dry shop vacuum. You can also use the vacuum to dislodge clogs in the drain line after they've been loosened with a small plumber's snake or auger. Use a combination of bleach and mild soap to clean and disinfect the drip tray. To disinfect the drain itself, pour a half-cup of bleach into the drip tray's drain line.

Next, remove the supply air vents and check the ductwork within. If you spot any mold or mildew on the ductwork, you may want to have a professional clean the ductwork without damaging it.

Preventive Steps

Prevention is the key to keeping dirty sock syndrome from making a repeat performance. Fortunately, there are several tips you can use to keep mold, mildew and the musty odors they create at bay:

  • Control indoor humidity levels - Keeping indoor humidity levels below 50 percent can help keep mold and mildew spores dormant. Increased ventilation through opening doors and windows and occasional use of a dehumidifier can help combat high humidity.
  • Invest in an ultraviolet (UV) lamp - When installed near the evaporator coil, UV lamps help prevent mold and mildew growth by attacking it on a molecular level. The UV-C radiation produced by the UV lamp is the same type of radiation produced by the sun.
  • Change the air filter regularly - Changing the air filter at least every 3 months not only eliminates a vector for mold growth, but it also enhances the cooling performance of your A/C system while improving your home's indoor air quality.

For more information and assistance with maintaining the A/C system, talk with professional HVAC contractors, such as those at Weather Control Air Conditioning, Inc..