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  1. #1

    Odor during defrost cycle

    Guys, I really need some help on this one.

    I thought the evaporator coil needed cleaning. When I got into the unit the coil was clean as could be. But, I was in there so I gave it a once over anyway and cleaned the drain pan but I still got the odor during defrost. When I discovered I needed to replace my ductwork I thought this would for sure take care of the smell but it did not. I only seem to get the smell during the defrost cycle. Any ideas? Let me know if you need anymore info and I'll try to provide it. Thanks in advance for your help.


  2. #2
    Join Date
    Jun 2001
    Louisville, KY

    Dirty Sock Syndrome or DSS

    Good luck!
    Perhaps you should have read the instructions before calling.

  3. #3
    Join Date
    Jan 2003

  4. #4
    Join Date
    Nov 2005
    toms river nj
    maybe the strip heater coming on during defrost. sometimes it there is enough moisture or dust in the air the can smell when it burns off

    may also have a problem forming with the strip heaters and should have a pro look at them to find out

  5. #5
    Join Date
    Dec 2006
    Middle Tennessee


    how do you know the coil is clean?

    did you shine a light thru the coil and see if you

    see the light thru the coil?


  6. #6
    Join Date
    Sep 2004
    I don’t always drink beer, but when I do I prefer Dos-Equis. I am the most interesting man in the world. Stay thirsty my friends.

  7. #7


    DSS is a problem. Unfortunately, OEM's are not often willing to help replace coils or take on any responsibility. Not enough studies have been done to determine total route cause. Hope the attched file helps explain it a bit further.

  8. #8
    Join Date
    Apr 2004
    Why should OEM's, distributors or contractors foot this bill? Nobody ever started a new unit with DSS, this, as the research suggests, is a bacteria growth on a coil after it is installed. Something in the air maybe. I've pulled a unit, donated it to a tech school (I didnt think the odor would be as offensive in a large open training mechanical room) and the odor disappeared after a few weeks. Amazngly, somehow, it seems something in that home's envoronment encouraged the growth of the bacteria and/or something in that tech school killed it. Non-the-less it went away. The best part (Or maybe I should say worst part for the homeowner) is the replacement unit, of another brand started stinking the next season. All ductwork was changed when the units were swapped out.

    Now this is not to say the HO is doing anything wrong, or lives dirty. It's merely an application or envoronment that we simply dont know what makes this happen.

    Certainly, there are things one can do to help slow or even eliminate it but the real question is why does it appear in so few systems and what is the common denominator in those systems? Short of sening in the entire Emory University Laboratory staff in with all their instruments, I doubt any real cause will be uncovered soon.

  9. #9
    Join Date
    Apr 2005
    Oh thats right it must be the homeowners fault for getting DSS. Most of the installers and manufacturers always blame the HO rather than looking at the equipment today. Tell me why my old HP didn't have DSS, but my new higher efficient HP developed DSS right away. I've researched this topic throughly, have reams of information on this subject, yet when I brought it up to the regional rep. he acted "DUHHHHHHHH, never seen this before", nothing wrong with our equipment, your the problem. Its about time the manufacturers step up, admit the problem exists, and make the simple cost effective change in the construction process to eliminate DSS from developing.

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