I've read other articles on a/c issues but still havent been able to figure out my problem.

I have an 01 GSR i just bought a/c stuff off a 96 ls. Ive checked all the fuses and they all appear to be good. I checked and realized that the harness from the 96 Ls is different than my 01 gsr, rewired and still nothing worked, no click over or anything. So i checked the voltage and im not getting anything from the main harness near the overflow resevoir. Any ideas???