Originally Posted by Diseasel300

This is your key. According to the electrical print posted by Frank in Post 49, the pressure switch is beyond the Klima relay. If grounding it turns on the compressor, you have no refrigerant in the system (you have tested the pressure right?), the pressure switch itself is bad (test for continuity across the terminals), you have a fault in the pushbutton unit or the "Electrical center" shown in the print, or you have a wiring fault somewhere.

Test for basics first, make sure there is refrigerant in the system and you have adequate standing pressure. If you do, test for continuity through the pressure switch. If those things are good, you have a problem further downstream. It isn't the Klima.