This thread might give you some ideas - http://www.peachparts.com/shopforum/showthread.php?threadid=68924&perpage=15&highlight=klima&pagenumber=2

As to where the Klima relay is in your car, I have no idea. But I imagine it's in the same place in any W124.

Sixto
95 S420
91 300SE
87 300SDL
83 300SD