I have pulled the connector off the blue sensor at thermo housing w/key on and the one working fan does come on.

I am working on getting a replacement fan for the one that has never worked. I found a place in Memphis: Wiley Imports, 3763 Old Getwell Road, Memphis, TN 38118 (901)362-3081 that "specializes exclusively in Mercedes-Benz Parts, Service and Salvage for over 30 years." They have been a great help so far.