A/C wires location and function

Hello every one, i have a 1971 datsun 240z with the after market a/c system installed on the car. I think the one what was installed from the dealer. The one that has the seperate turn knob usually mounted unter the dash board. Well anyway, at some point somone installed an alarm system in the car that was wirerd in with the wiring harness a real mess, and it did not even work. So in the process of removing that junk, i think i might have clipped the wrong wire because now my a/c system does not blow cold. ( please note that everything else works as it should) So if somone could tell me where the 2 leads go coming from the back of that a/c turn knob switch i could verify and trace them down...if there was any doubt as to the interegity of the wire i could just re-run them. If somone could help me out this would be great. I really dont see the need for a pic for this question but.....i will be more than happy to do so if one is requested. I look forward to hearing from everyone