Sorry for so many questions! I know I've been asking too much, let me know if should stop.
Ok, so I had the A/C on today (77 degrees outside) and noticed that the passenger side vents were blowing hot air from the far right vent as well as the winshield vent, all while the driver's side was blowing cold. I searched the archives and found that previous owners with the similar problems have been led to the duo valve as the culprit. I called the local dealer and it was $203.00! Any cheaper source? Can I get it used from a wrecking yard or other source? Anyone have one lying around they want to sell?

Also, I noticed that while the A/C was on, the air kept switching by itself from the windshield vent to the center vents. It would switch about every 30 seconds and not in a fixed pattern. Is this also due to the Duo valve? My car is an 1995 C280. Again, sorry for the many posts and questions.

 

Yea, www.mercedesshop.com. write to Phil and if you have a part number give him that. I bet his price is a lot better then a dealers. I get a lot of parts from him and all are OEM and I have paid as much as 50% less then at the dealer. Some aren't priced that low, but you will save at least 20% and free shipping on any order over $100. Good person to deal with, he sent me the wrong part. It was for someone elses car and he had UPS pick it up at my house and he refunded the price and S/H, as the order came to $78 or so.

 

I fixed this same problem on my 97 C230 about a year ago. I usually get parts from Caliber Motors in Anaheim Hills, CA. They are an MB dealer and have a wholesale parts operation. I think I bought that particular part from Autohausz in AZ Sp? at a friends recommendation who owns 4 MB's currently. I think I paid about $179 for the part. Pick up some official MB coolant too to top off when done as some will inevitably leak out during R&R.

If you have larger hands/fingers, it is a tight job. I chewed up my hands real good.

Good luck.

Mark

 

I too have the same problem in my 2002 C200.
Where is this Duo valve located?
Could it be replaced by DIY or need I send the car to a MB workshop?
Thanks.

 

I think the duo valve is located under that cover in the top left hand corner under the hood. it looks like 2 double A batterys. If your AC is on and its notblowing cold air in the middle, give it a hard but firm tap with a rubber mallet and see if it starts blowing cold air, it can get stuck sometimes