I have a 1984 MB 190-d, about a month ago, all of a sudden the tach stoped working along with the A/C compressor, the blower still runs o.k. I have tested everthing that i can find. I have changed the rpm sensor on the starter bell housing, tested it, and it is within specs. I have tryed jumping pin 5 and 7 on the 12 pin climate control by the battery, according to my trouble shooting sheets, when i do this the compressor is suppose to engage, but it does not. and the trouble shooting does not go any farther than this.

Can anyone tell me what to check next of jumping pin 5 and 7 does not turn on the compressor?

I am at a total loss right now, i have been working on this for over a month and can not track it down.


HELP.....Please !!!!!!!!!!!!

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1984 190D 2.2 (the real one not the 2.0 bored out)
1994 Saturn SL1
1994 Jeep Cherokee 4.0