Hi Guys,

I need to ask a question, well maybe two questions.
There are three wires that go to the compressor on my 1990 300E. Which one of them powers up the compressor clutch and what do the other two wires do?

Thanks guys,


Nina XOXOOXOXOOX

One is 12 volt power and the other two are likely the RPM signal. The AC system checks the RPM of the compressor and compares it to the RPM of the engine and if they are not similar assumes the compressor is slipping and prohibits the compressor clutch from engaging. Climate control wiring diagram on the service CD will show which color is which.