A/C Wiring diagram

[1972ChevyCheyenne]

I am trying to figure out my fan switch on my 72 for the blower fan. I need a diagram for the A/C wiring. I looked in the assembly anual but didn't see anything. Currently I have 2 wires going out in front of the cab. 1 dark green with must go to the compressor and a 12-14 gauge purple which I think goes to the blower fan. The part in the cab is confusing me though. On Heater fan switch and four wires do to in i think the brown is the power feed and the other 3 (blue, yellow, orange) go away from it. Where? Also what is the purpose of the resistor and the micro switchon the heater box? I also have about a 14 gauge orange wire that comes back toward the heater switch that I am unsure of its purpose. A wiring diagram would be great or a location in the assembly manual would help. Any other info would help too. Thank

Jamie