Quote:
Originally Posted by howardjnl
Diseasel300, Thanks for the feedback. Confirms what I was beginning to suspect from reading other posts elsewhere. GERMAN AUTOMOTIVE has the side of the cube relay coil opposite the side going to Klima pin 10 being connected to Klima pin 1, a ground connection. That led me to believe pin 10 would provide power.
So, instead of pin 1, I'll use the power source from pin 5 to connect to the relay coil opposite the connection to pin 10.
THE COMPRESSOR RELAY CAN BE BYPASSED AS FOLLOWS:
1. USING RELAY # 001 542 02 19 MAKE YOUR OWN JUMPER WIRES.
(P/No. Mercedes A 0015420219 / Hella 4RD004122-00)
2. TERMINAL #5 ON KLIMA TO #86 ON ICE CUBE, (Solenoid lead) (Klima power input)
3. #10 KLIMA TO #85 ICECUBE, (Solenoid lead) (Low pressure switch gnd input to Klima)
4. TERM. #5 KLIMA TO #30 ICECUBE,AND (SPDT common) (Klima power input)
5. #7 KLIMA TO #87 ICECUBE. (SPDT NO) (Klima output power to compressor)
CLUTCH WILL ENGAGE AND DISENGAGE AT PUSHBUTTON ASSY'S COMMAND
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I misspoke earlier when I said #10 was a ground. #10 is an output signal generated by the Klima and pulled down to ground by the ACC.
The Klima will output a voltage on #10 (~11V on my car) which the ACC pulls down to ground through the refrigerant pressure switch. It doesn't pull all the way to 0, I measure ~.8V like Frank does. The reason it doesn't go fully to 0 is because the switching is done by transistor in the ACC unit on '86+ models, they can't pull 100% to ground, the idea is to pull the signal "low" which tells the Klima to go ahead and engage the compressor.
So to recap, Klima generates voltage on #10 and if the pressure switch is closed (you have enough refrigerant), the ACC pulls #10 down to ground (low).
In my car, I found a failed darlington transistor pack in the ACC unit that caused it to fail to pull down. Rebuilt the ACC and it's been working like a dream.