Ok, I have a 5.3 from a 2003 Silverado. I'm working on the harness and I'm trying to figure out how I'm going to wire the A/C. As I understand it, the ECU receives a signal from the BCU over serial and turns on the compressor clutch. My question, is there another way to directly signal the ECU to turn on the clutch? Otherwise should I just power the clutch directly? I'f possible I'm trying to make A/C switching seamless. Thanks.