Trane XE80 cleaning question

I have a Trane XE 80 A/C, gas heater combination unit. For a few months now, there has been a "musty" smell. My A/C guy checked it out and put a liquid chemical cleaner behind the filter that was then spread through the system via the fan (it was not applied to anything directly). That seemed to take care of it for a while, but now the odor is back. Also, the filter, which I replace regularly (3M), has moisture collecting on it to the point that the metal stabilizers in back sometimes have some rust on them. I mentioned this to my A/C person as well, but he just says neither he nor his boss have any idea what might be causing this accumulation of moisture. He also claims the inside part of the A/C unit is "self-contained" and cannot be cleaned (he serviced the condensator (?) outside and cleaned it). I would just get another A/C person, but I have a maintenance contract with these guys (long story of company resales) and would loathe to pay someone else to come out if there's nothing to be done.
I have searched the hvac forums in vain for any information on this type of problem with the XE 80 or even a comparable Trane unit (everybody else just seems to have issues with the gas heater auto ignition). Any ideas? I also searched for a schematic to see whether the unit is really "self-contained" and "doesn't need cleaning" as the A/C guy stated, but I have had no luck there either (Trane's website doesn't list the XE 80 anymore). The unit is 10 years old and mostly used for A/C. Apart from the odor, I have had no issues with it. The odor clearly seems to originate near the unit and not in the vents.
Thanks for any help in advance! KB
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The indoor cooling coil which is most likely in an enclosed sheetmetal supply plenum directly above your furnace CAN be cleaned. Keep in mind though, if it is in the supply plenum and it has no door or access then it is customary to charge extra to clean it. It involves carefully cutting a hole in your plenum to access the coil so as to avoid puncturing the coil. The coil needs to have a chemical applied to it (from Trane) to get rid of the smell. It sounds like you are describing what is called "Dirty Sock Syndrome". (Google It). Cleaning can help but for the most part, replacing the coil with a new one is the only way to completly rid yourself of the plenum. Lastly, if someone cuts a hole in your plenum, have them repair the hole with a "split door" so next time you can just slide the door open to access the coil. It'll save you that extra charge next time. Thats the difference between a "Tin-Knocker" and a sheetmetal craftsman. Bubba
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wrote:

Thank you very much, Bubba! I will mention this to the A/C guy and if he won't do it, I'll find someone else! At least it sounds as though this is "do-able". Also thanks very much for the "split door" hint. That makes a lot of sense!! KB
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I meant "problem" above, Not "plenum" :-)

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I figured as much, Bubba. Thanks for clarifying though! Also thanks for the link, Stretch! Good article, and the information from both of you will help me ensure that the job is done right (or at least it'll give me a better shot at ensuring it. ;)) KB
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Try this link
http://www.contractingbusiness.com/25/TechTips/Article/False/6025/TechTips
Stretch
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