Mike,

While I don't profess to be an expert by any definition, I did have similar issue with my 82 107. I might suggest you contact a company called Programa (not sure of spelling) as they are able to rebuild many of the control units. They may be able to help you determine if it is your control unit that is failing or if it another component. If you don't have a Freon leak it has to be a component.

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82 380SL 41K miles sold, 98 SL500 44K miles, 13 C300 4Matic, 14 CLA-250 4Matic