Working with Mercedes and driving one every day I come across many diffrent problems. One of the problems I am going to talk about in this thread has to do with the Heater and AC.
Upon driving my Mercedes with the heat or AC working I would notice every once and awhile an almost Toxic fume emit from the vents, usually when the blower motor speed changed from high to low. My first thought was possible tampering with the ventalation system, however I soon realized this idea was more or less a result of watching too many movies.
What I did find after inspecting the system is the Blower Motor. While I think the blower motors out last many others out there found on diffrent makes, the design of the Mercedes Benz blower motor found on the W126 model is not without flaw.
What I found is that a blower motor that is near death runs much hotter than one that is in good condition. What has been creating this "Toxic" smell as I would call it, was the fact that the blower motor is surrounded in a plastic casing. When the motor overheats this causes the plastic to melt, thus pumping that awful smell thru the vents and into your nose.
The fix is somewhat simple. Just replace the blower motor and the smell goes away. Amazing just how strong the smell can be at times, however melting plastic has always given off a very strong "Toxic" smell. You should also note that melting plastic is in the "Toxic" realm.
If you are smelling something coming thru your vents, and it is not constant or goes away with differing blower motor speeds its best to remove the blower motor that is located under the dash on the passengers side and inspect the unit. You will most likley find that your blower motor is melting away the plastic housing that the motor itself sits in. If anyone needs photos of how to remove the blower motor please respond and I will post detailed instructions within this thread. I am also going to post photos of my defunct blower motor and the melted plastic once I get the chance. Hope this helps.
__________________
What is to give light must endure burning -- Viktor Frankl
It is also important to test and replace (if necessary) the blower motor regulator when changing out the blower motor. Often the regulator is the culprit for a non-operating blower fan, not the fan itself.
Also, don't cheap out and get inferior quality Chinese-made junk blower motors. Get an OEM unit from Behr or an MB unit via parts.com. For some cars these motors are getting harder to find, even from MB. I have been told in the past year or 18 months that the blower motors for the R107s are no longer available from MB.
