My stinkin Haynes manual says it goes through '85 but the wiring diagrams only go to '84.

Does anyone have a wiring diagram for the '85 300 D??

I have 7-8 volts at the ETS not 12. I took my push button control out and installed it in another 85 and the A/C worked fine in the other car.

This is very perplexing and I dont know what to do.

I would like to suggest changing all your fuses..............IF you still have an issue after replacing them let's see where we can go. While you are replacing the fuses push the spring loaded tabs downward, this will increase the force exerted on the fuse tips ensuring good contact!

Ok I will go and do that now.......

Ok all fuses are now more reliable copper and I even tested each fuse for contunity.

Still no change. Only 7 volts at the ETS. :(

Is that with one of the wires disconnected from the ETR (Evaporator Temperature Regulator)? If not it is possible you are measuring the voltage difference, or voltage drop, across that part of the circuit. Try jumping the two wires to each other (bridge) and see if you hear the compressor activate.

Your vehicle should have either a “compressor relay” or a “kick-down relay”, do you know which one is fitted to your car?

The micro cutout switch is working properly and the compressor relay is inside the Klima relay on the 85 Model.

I finally gave up and took it to the Mercedes Indy. 2 weeks of messing around was getting me no where. Sometime you have to recognize when its over your head. And it was over my head. :vbac47679

Please keep us apprized of their findings, it helps us better understand what we may have overlooked during this process.
:cool:

It ended up being the evaporator temp sensor. I believe MB Doc had mentioned that. I got fed up with it and took it to a Mercedes Indy. In fairness it took them ALL day to find the problem.

It is fixed now and I am changing out the compressor, drier, expansion valve, flushing, BG oil and Freeze 12.

I should have it done tommorow and blowing COLD!