If you want to do it correctly yes.
The ac compressor should be controlled by the g body ac controls but you still communicate with the LS computer. The LS ECM controls idle bump and coolant fans that just using the g body control won't get you. However there's things in the g body harness you need like blower fan power, cycle switch and on signal you want to keep.
I put this video together since nobody seemed to describe how to do it.
Basically you give 12v to the compressor and tee off to the LS ECM to do the fans and idle if you don't want to go through the hassle of commanding the ECM and having the ECM go to a relay to trigger the ac clutch.
If your using a OEM variable displacement compressor you should use the entire LS ECM with the high and low side pressure switches but if you have an on/off style R4 pancake or sanden compressor this is the cleanest way to do it.