I have relentlessly been tracking infro on Klima relay problems on my '85 300TD.
Have read the relevant posts, but need a few pieces of practical info from soneone who has been there.
I have both 12v dc and the 12v control signal from the ccu at the Klima socket. The control signal goes off when the ec button is pressed, and comes on again for any of the other options, including, for some reason, defrost.
So, if I have 12 volts to kick in the compressor clutch and 12 volt control signal, I should be able to jumper the relay and get the compressor running, right?
My questions: Is there another Klima board, behind the battery, let’s say, on the '85 TD. or are all the Klima circuits built into this $240 relay? What else does this Klima relay monitor or control? I understand the '85 circuit on the 123 is different from all others, hopefully less complex
Which pin on the relay socket controls the compressor clutch? I don't want to backfeed 12 volts into a solid state circuit in the wrong polarity.
As with my 84 123, when I jumper the hot pin to the compressor clutch, the clutch should engage for a test.
I need to make this simple test on the 85 to decikde whether to replace the Klima, tear it apart for a rebuild, or simply replace it with a much simpler ice cube relay. My experience is that inept probing with a hot 12 volt line can do some damage.

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Stage Wizards Lighting and sound designer
1981 SD 328,000
1985 300TD, 266,000
1984 300 TD, 267,000