2015 Peterbilt 579 a/c compressor has no power!

I have a 2015 579 with a Paccar engine. The a/c quit working suddenly and I can’t seem to figure it out. I have no power to the battery side of the relay. I have power to the “trigger side”, but no battery power. I can’t seem to find a wiring diagram to see where the relay sources battery power from either. The compressor has good ground, and I replaced the pressure switch thinking that may have the battery power directed through it, but that didn’t work either. I’m getting power to the 5 amp fuse for the a/c head and all of the functions are working fine. No power to the battery side of the relay. Is there another pressure switch somewhere I don’t know about? Any help is appreciated. Thanks.