help!....ac wiring and relay location on 97 jetta

Hi all,
I have a 1997 Jetta Jazz, and the there is a problem somewhere in the ac wiring. The compressor no longer kicks on when I turn on the ac switch on the dash. I tested the wires going into the button itself, and there was very little juice getting to it. I assume there is a short in the wiring between the button and the compressor, and/or the relay is bad. I have been totally unsucessful in finding out which relay is for the AC so that I can try and feel if it is clicking on. Any help is appreciated!!!
Kelly