I have a 99 sierra 5.3 4l60. My ac went out a few years ago (leak at compressor) I finally decided to fix it. Changed ac, drier, vacuumed the system, everything will work if i jump it from the relay its ice cold but it will not turn on with the control inside. I have bypassed the high, low switches still wont work. Took it to the dealer they said it was my ac controls inside the truck. I have tried 3 of those, 1 of those in another truck so i know it works. Took back to the dealer they say it's the PCM. Does this sound right? I dont know what else to do. Has anyone had this problem or know what else to try? Thanks in advance