Guys, I made up an assembly based upon my drawing and works as it should. I appear to have everything but the compressor speed sensor function just as planned. Currently using ice cube relays with 85 ohm coils as described in my previous message.

Howard,

Did you connect both KLIMA socket pin 4 (WOT micro-switch) and pin 12 (High temp micro-switch) to the same point on the relay (pin 85)? If you did not, why not?

I think that should work fine.

I'm going to be using one of these for the control relay:

https://www.digikey.com/catalog/en/partgroup/acvn-series/52005?mpart=ACVN51212&vendor=255

It has a 180 ohm coil, and has a standard DIN layout. Four bucks, cheap insurance, just in case the 1A "rating" is a bad guess. The other relay will be a regular Din style switchover relay.

That relay should be fine for your needs. 180Ω is the usual impedance of a PCB or "ice cube" style relay. It is worth using the correct relay to preserve function of the darlington pack in the ACC unit, they can break down easily if overloaded. My SDL had a bad darlington pack that had the module controlling the Klima relay fail in an open state. The darlington pack is no longer made and has to be sourced from existing stock, not easy. The cutout relay can be anything since it isn't transistor switched.

According to the schematic for my particular '87 300TD, pin 12 is not used. So I did not hook it up. Attached is a portion of the schematic, I couldn't upload the whole thing (too large a file).
Note too that other versions for '87 diesel include another relay on the left (K8). Mine only has K9 and K10.
John

The later cars did away with the Klima controlling the kickdown solenoid. I think 1985-86 were the only years that had the Klima controlling kickdown. I know 1987+ W126 did away with it. I'd assume the other models were similar.

The kickdown solenoid on my '87 190DT is powered through the Klima. Powered is the operative word...the Klima only controls it in the sense that if the Klima fails, you have no transmission kickdown. I think the idea is that if the Klima shuts down due to belt failure, it's a good idea not to run the engine at high revs. On most of the gas cars, kickdown power is supplied through the fuel pump relay.

Pin 12 is the coolant thermoswitch. With some versions, the ACC (rather than the Klima) will control fan and compressor using a thermistor rather than a thermoswitch.

Not enough coffee in the system. Too long of a Monday...

Right, the coolant microswitch - Not sure of the cutoff, but later cars (I know the 350SDL and 2.5 Turbo W124) used the thermistor in the head and had the ACC do the high temp cutout control. The number of variations in the Klima relay is truly ridiculous over the years. It's almost like they changed it every year! I guess the good news is that they all seem to use the same pinout, so if in doubt, the '86 version that used all of the pins should work for any of them.

What amazing info! Can you guys tell me if this would work too on a 1987 190D 2.5 no turbo, manual trans?

I just would like someones okay who is in the know to give me the go ahead as I don't want to burn up anything - thanks!

It works fine on my '87 190DT, that's my only data point. At some point, I'm going to tear into the EDS unit and replace the caps. That should allow the Klima to work as intended.

You lost me on ..... "EDS unit and replace the caps"
What is that?
So does your A/C work currently with this Klima bypass or not.

OMG--- on my 87 190D I have no pin #4! According to the last and latest bypass diagram that should be the "A/C cutout switch"
The hole is there but no wire!

Now .... what......

Really need some direction from someone please!

I use two relays, the diagram is in my post. It works fine, but it bypasses the compressor cutout. As long as my compressor doesn't seize, no problem.

The reason the Klima isn't working is that the EDS computer, which controls idle speed, EGR, and various RPM sensitive functions, isn't working well. It intermittently fails to produce the correct speed signal, which affects the Klima. Diesel300 posted a few months ago on replacing the capacitors on the EDS circuit board, and I just haven't had the time to do it. I expect that the Klima function will return to normal if the EDS computer is working correctly.

There is no pin four on manual transmission cars.