It is a good practice to make sure all of your dip switches are set to the factory position on all of your flow selector boxes during installation. If the dip switches are not set in the factory position you will have L11 and E17 error codes to follow. You can verify the factory dip switch settings by looking at access door on the flow selector box. The L11 and E17 error codes can also be caused by wiring issues, good wiring practices can prevent having problems.


Changing dip switches on your flow selectors is not necessary because all of your flow selector addresses and port numbers are set using and codes 00FE and 0105 on your thermostat. Making sure your flow selector address and your flow selector port address is correct will make the start up process much easier. If care is taken and you have a good understanding of the wiring and installation of a VRF system the start up process can be close to seamless.


L11- Detected indoor unit address, Flow selector unit not connected.


E17- Communication trouble between indoor unit and flow selector unit.

Gulf Coast

Technical Service Manager

July 9, 2024

Dirty Sock Syndrome

What It Is and Isn’t


Dirty Sock Syndrome isn’t about flawed design or material in HVAC systems. It’s a term that might not be familiar, but the phenomenon is unmistakable. When an air conditioner emits a moldy, foul odor that resembles dirty gym socks, it’s a clear sign of Dirty Sock Syndrome.


Identifying the Smell


The smell of Dirty Sock Syndrome varies but centers around decaying organic material. Technicians often find that homeowners become desensitized to the smell due to constant exposure, similar to how individuals get used to their own body odor. The odor is usually more noticeable after the house has been unoccupied for a few hours.


Causes of Dirty Sock Syndrome


This syndrome is caused by mold and bacteria accumulating on the evaporator coil. Continuous moisture promotes mold and mildew growth, while dust particles contribute to the problem due to poor filtration.


Detecting Dirty Sock Syndrome


While the distinct smell is a primary indicator, other issues can also cause bad odors. Technicians should first rule out other potential problems. Check and ensure that drainage pans are empty and free from rust and damage. Clear any blockages to prevent mold and mildew growth. Wet filters and blocked drainage lines also indicate issues.


Risks Associated with Dirty Sock Syndrome


While not usually dangerous, Dirty Sock Syndrome can pose health risks if mold spreads through the HVAC system. This can cause respiratory issues and eye irritations. It’s important to address the issue promptly to prevent the odor from affecting the household’s well-being.


Preventing and Treating Dirty Sock Syndrome


Prevention is key. Always use high-quality filters and replace them every one to three months. Installing UV air purifiers can prevent mold and bacteria from compromising the evaporator coil. UV lights effectively kill mold spores and bacteria, providing additional protection for the system.


If Dirty Sock Syndrome is already present, start by cleaning the evaporator coil. Although homeowners can attempt this with homemade solutions, it’s best handled by professionals trained in HVAC cleaning. Replacing clogged or wet filters ensures proper filtration and airflow. Technicians may also need to clear blocked drainage lines, often with a shop vac.




Sources:


HAVC Partners, POL224.00 APP Guide, IIK-CRECON-SRT-01


Disclaimer: The technical statements, information and recommendations contained herein are believed to be accurate as of the date hereof, but Mingledorff’s does not make representations or warranties, express or implied, as to its accuracy, its completeness, or the results to be obtained. The information is being provided for informational purposes only and is intended for use by persons having adequate skill and expertise regarding the proper selection, use and application of the products and recommendations and at their own risk and discretion.


More to Explore

September 16, 2026
Disclaimer: The technical statements, information and recommendations contained herein are believed to be accurate as of the date hereof, but Mingledorff’s does not make representations or warranties, express or implied, as to its accuracy, its completeness, or the results to be obtained. The information is being provided for informational purposes only and is intended for use by persons having adequate skill and expertise regarding the proper selection, use and application of the products and recommendations and at their own risk and discretion. 
By Jesse Van Atta • September 16, 2026
Disclaimer: The technical statements, information and recommendations contained herein are believed to be accurate as of the date hereof, but Mingledorff’s does not make representations or warranties, express or implied, as to its accuracy, its completeness, or the results to be obtained. The information is being provided for informational purposes only and is intended for use by persons having adequate skill and expertise regarding the proper selection, use and application of the products and recommendations and at their own risk and discretion.