Are mass control units universally interchangable if visually they are the same? Specifically, my part number is 008 545 8132. I may have access to PN 7932 from a 1990 300E, or 8532 that I am told may be from a 300SL. The reason for replacing my original is that the air compressor does not work. Upon doing some diagnostics and swapping a unit from another car (91 300E), the compressor and ac worked perfectly.
I physically do not have access to the 2 units I speak so if any one knows the interchangibility, it would be a great help.

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Walter Sawczak
1990 300 E
1993 Lincoln Mark VIII
1983 Jaguar XJ6