Geo Prizm AC clutch Fix

Hello.
I've been keeping my trusty Geo Prizm going with parts from pick and pull.fo a while now. The latest problem has me stumped. The the ac stopped working- no light on the switch. I tried wiring the compressor straight to the battery and found that the system works fine, just that the switch wiring must have a break somewhere. I'd just leave it hotwired for the summer but it drains the battery while not running.Can someone advise on how I might locate the electrical fault in the clutch wiring? Many thanks...