Thanks very much for your reply. I have the same problem you described, nothing worked and as I indicated I located two "fixes" to at least find that the compressor worked and I can get heat. BUT, I also have problems with opening my trunk lid after locking the car I suspect that a vacume problem does exist. Could you tell me where the "main vacume switch" you refer to is located and mabey how the toggle switch was installed, that is, into what circuit and where located. Even if I can't do it myself I have a mechanic a few miles away who used to work in a mercedes shop in Kansas City. He told me he wouldnt touch anything climate control related that was under the dash, but if I could point the way he would probably help me out. Again I really appreciate you response and hope you may be able to supply the additional information
Sincerely Lee Hazel