Does your A/C smell musty when it first turns on?

"Dirty Sock Syndrome" is caused by a bacteria that collects and grows on the indoor coils of heat pumps and air conditioners during the heating cycle. Complaints typically happen after heat pumps run in heating for a brief time and then are switched back into cooling mode. In Sarasota, we have numerous days where the temperature reaches the mid 80’s during the day requiring air conditioning, then into the 50’s at night requiring a little bit of heat to “take the chill out of the air”. This pattern is a perfect recipe for creating and releasing the bacteria and odor that collects and grows on the coil. 

Do I have Dirty Sock Syndrome? 

The odor is commonly referred to as a musty smell, and is only present during AC operation. In order to determine if Dirty Sock Syndrome is an issue at your home a qualified technician should visit and rule a few things out such as: 

• That your indoor unit is draining properly and standing water is not sitting in the primary drain pan.

• That all drains are trapped and vented properly

• Insulation inside the indoor unit (air handler) is not wet 

• Duct leaks, especially on the return side are not present 

• That your home in not excessively “leaky” and the smell is not from air infiltration. 

How does Dirty Sock Syndrome happen? 

Dirty Sock Syndrome is estimated to affect between 1.5 and 3% of heat pump systems in the Sarasota area. It is not brand specific with all Manufactures acknowledging complaints. Though Manufactures have spent a lot of time and money to identify its exact cause no one has offered definitive proof.  Most research agrees that it is a by-product of Micro-Organisms that grow on the indoor coil during the cooling season and feed on the minute particles produced by common household items such as cleaning agents, perfumes, cooking, hair sprays, dust, etc.  This would explain why equipment removed from a home that suffers from Dirty Sock Syndrome can be installed at a different home and never have a similar complaint. The Micro-Organisms are dormant during heating but are reactivated during cooling and that is when the odor is released. 

How do I get rid of it?

The most cost-effective way to get rid of Dirty Sock Syndrome is a simple evaporator coil cleaning. This typically solves the issue and should be done as part of a pre-planned maintenance program like the one we offer. If regular seasonal cleanings do not work the coil should be cleaned again and a coating of Alathene or Rep-60 should be applied. As a last resort the coil may need to be replaced and that coil should have a factory coating applied to it in order to ensure the problem is resolved. 

Dirty Sock Syndrome can be frustrating and consumer complaints are generally aimed at the installing contractor. While some contractors are ill-equipped to deal with Dirty Sock Syndrome and that increases the consumer’s frustration, we should all keep in mind that airborne contaminants being circulated from inside the home is the root cause and is a difficult hurdle for even the best contractors to overcome.

If you believe you have a problem with DSS or would more information, feel free to call our office at 941-378-2080