Pc300-8 a/c not working

Hi guys. I'm looking to see if anyone can help me out. I have a komatsu pc300-8 and the a/c is not working. This machine will be shipped to Alabama and so the a/c need to function. I have no power to the high pressure switch under the cab. I've been looking for a wiring diagram. If anyone has one I'm willing to pay so I can trace wires. Fuse for the a/c is fine I tested that. Do not know if there's a relay for this system or not and so I am now in search of a service manual for my machine. Anything helps Sincerely Nick