Sportstick

Yes, each to his own, but did not want to leave this question hanging...

A/C off allows moisture to remain within the system, which creates the conditions for mold. A/C on takes the moisture in the air and on the coil, condenses it into water, which drains through a drip tube, leaving behind a dried system. The goal is to get rid of the moisture, so some degree of A/C on addresses that, and the AUTO function does it for you.

acr2001

Respectfully, you should reconsider the logic behind this. It's completely wrong. AC on means water is condensing all over the fins and the entire heater box is wet - dripping with water. With the compressor off (unless it is an extremely humid day) the incoming air hitting a room temp coil will actually dry it off which is impossible with the compressor on. This is why the engineers designed the fan to come on low when the car and the AC are off in order to dry the system. If the car had no AC compressor at all, there would never be enough moisture to cause mold.

Sportstick

I appreciate your point, but in actual application, the theory runs into the issue of low/partial use. We agree, a car with no A/C and just vents/ducts will not have the problem develop just from ambient humidity. We also agree that using the A/C causes condensation. I think where we diverge is that little/low use of A/C allows residual water to remain, while more frequent usage eliminates the residual. Perhaps the key is replacing older residual with fresh condensate, but in any event, the media for mold growth is eliminated with usage. On the road experience does show that, but for some of the heroic measures described above, those who use AUTO seem not to have the problem, while those who have the problem seem to be those who manually intervene. Even my greatest colleague-in-debate, Doanster, acknowledges that!

jctevere

Yeah, I completely agree, I used to manually run the a/c and such, and used to get that mildew smell. I now use AUTO and rarely EVER get any mildew smell. And if I do get a slight one, it isn't nearly as bad as when I manually adjust it, and goes away within a few seconds.

Also, it seems that if you take short trips (under 5-10 minutes) consistently, the mildew smell is worse and more common than longer trips. So I try to use the windows as much as possible in the summer months for longer trips. But now that winter is rolling around, I'm starting to use the A/C for 76 to warm up with my heated seat!!!

acr2001

Alright, now you guys are making sense! I like this idea because it should help prevent stagnant water by refreshing it constantly. I used to mess around with my w203 manually all the time always turning the AC function off especially in the winter when it would run on low to prevent humidity. I'm going to just keep it on auto myself. If it stinks the dealer can deal with it. Good thread

Sportstick

Glyn M Ruck

https://mbworld.org/forums/attachmen...y-a_c-odor.pdf

Doanster

You beat him into submission. What a bully!!

acr2001

Sportstick

Ask my kids!





He held his own just fine!

ayejoel

Hey guys. I have the same problem with smell from the a/c and decided to call the service guys at my local dealer about the service bulletin. He informed me that another bulletin had came out just recently that stated the problem wasn't the evaporator as the sprays did not work. He said that changing the cabin filter, charcoal filter, and pollen filter does the trick. Now I know how to change the cabin filter which is a pretty simple task, but what is the charcoal and pollen filter? From what I can tell from some research online, they are all the same thing, as in the cabin filter is the pollen and charcoal filter. Can someone clarify this for me?

Glyn M Ruck

Some cars don't have charcoal filters. Any chance of getting hold of this new bulletin. It does not really make sense. I've seen bacteria growth on evapourators so bad that they require replacement. Newer evapourators all come microencapsulated with a bacteriacide.

ayejoel

I don't have any way to get the bulletin. The service guy told me the bulletin came out this month(MBUSA). My understanding from what I've researched online is that the cabin filter, charcoal filter and pollen filter are the same thing. Am I understanding this right?

RLE

There is only one filter which is behind the glove box. Accessible from below.

acr2001

Sounds like he's lying, just like most dealers. It's expected behavior from them at this point. If MB is in fact no longer offering cleaning of the AC units then they are lying themselves that a simple filter change will eliminate the problem. Changing the filter rarely fixes the issue and only at the onset in my experience.

Glyn M Ruck

+1 - You need to get the evapourator & all the ducting sterilised.

Distalero

Or, you can conduct a really uncontrolled experiment, like I did, by shipping your car from one well known moldy environment in Northern Calif, to the island of Maui (the near tropics) where mold is also way of life, in order to let all those little moldy beasties encroach on each other's territory so they duke it out, see who's dominant, hoping that they severely injure, or tire, each other enough so they take a long, long time out.

Or.....maybe not; the smell's still there

acr2001

I was about to book a flight until your last line...

alexlev

Febreeze it.

Distalero

Actually, after the last dealer treatment in Northern Calif that odor was pretty mild when it finally came back, and only intermittent, so I find myself in a kind of gray zone, but I can hang.

Is there any merit to my experiment? Hell no, but no new smell, and not much of the old smell, so maybe the Calif beasties are dominant, but off being tourists? My next experiment is to try little bits of spam musubi close to the filter, see if I can coax anything out (other than the usual 2ft long roaches, maybe a gecko or two, etc).

ayejoel

Just wanted to give an update in case it may help anyone. After calling the MB service guy I ordered a cabin air filter online for about $17 US. While waiting for it to get delivered I also ordered some of that Klima cleaner. Used the cleaner through the center air vent like instructed and the smell was still there the next day. I'm sure it cleaned the evaporator, but did nothing for the smell. After a couple days the cabin air filter came in and I installed it(very easy and painless procedure). The next day there was no smell. It was completely gone and still is since the filter replacement. After the installation of the filter I went to turn my car on to check the a/c and it wouldn't start. It turned out to be the battery, which I replaced myself(also a pretty easy and painless procedure). Since replacing the battery I noticed my car shifting much smoother, it seems like if the battery is bad or weak the car's computer makes it shift weird, or maybe that's in my mind? Either way it shifts much smoother now. So just to help out, if anyone comes looking for help with a stink in their 2008 C300(which is what I have), order a cabin air filter right away and change it. Thanks to anyone who helped me on here.

rexi01

Where did you buy the filer?

ayejoel

http://www.ebay.com/itm/Cabin-Air-Fi...75246785464322

$17.50 US with free shipping.

hhh818

do you guys know what the resp button is for? just beside the a/c button. i pressed it a lot of times nothing happens. always wondered what that is for.

Sportstick

Good news!

Now, put it in AUTO and leave it there unless some short-term unusual condition exists...and afterward put it back in AUTO again.