Originally Posted by Gilly

Near the battery. If the car has all it's original do-dads, there is a black plastic panle behind the battery, this can be removed by hand. The relay is back there. On top, amongst all the part numbers you will see that it says "6 ZYL" on it (6 cylinder), and also list an RPM, which is the safety cut-out rpm. The one that says "KLIMA" on it is the relay for the AC compressor, looks just like it otherwise. You'll also see a small metal relay with a clear door on top with a fuse or two under that door, that's the famous "OVP", overvoltage protection relay. Couple big control modules back of that too, engine, ABS modules are the big guys.
Gilly