Date registered: Dec 2005
Vehicle: 222.132 & 221.122 & 212.025 & 906.633
Mentioned: 3 Post(s)
Quoted: 32 Post(s)
Hi, are you talking about the air ducts that are not "under the front seats" but instead to the front of the front seats, in the centre walls of the leg area? Honestly I started to hesitate on those even if I've played many times installing and uninstalling the hoses (on my W211), those must be the hoses that blow air to the leg area instead of pulling air. Now that I think of it, I've never figured out where the air circulation mode pulls air but if you do not have air circulation on, it can't be those ducts that you described (if I understood correctly). There are ducts below the front seat too but those blow air to the rear seat area (and at least do not pull air). It should be easy to test which duct is pulling and which is blowing air.
Anyway, you seem to conclude that the heater/air conditioning system pulls air from an area of the car that smells. That should not be the case (again assuming air circulation mode switched off).
Would your odor actually come from inside of the heater core, bacteria smelling as those tend to grow from the condensed water from AC. There are posts on the W211 of this problem as I understand early models having a small design issue, condensed water not getting all out of the system when car stopped or something like that). If it is this one, then your car could be treated with some stuff that kills these bacteria, see the W211 forum, should work for a year or so. I guess this is more of a problem if you live in a humid climate where AC is frequently used and a lot of condensed water appears. (Unfortunately I live in an area where this is not too much of a problem ;-)
If the smell really comes from the foam layer behind the loose mats, I would easily conclude that there is some water leak or the user has spilled some stuff to the car (which I understand is not the case if you have taken good care of the car).
PS. I don't think Ikchris intended to be offensive, at least I took it more as a request for more info because the conclusion otherwise would be "a user fault". Experts might respond if they don't get a feeling their response might not be appreciated.