My brother and I have been having the same issue with our trucks this year. That being that the AC compressor clutch would not engage, despite the AC systems being in otherwise solid condition (no low refrigerant levels or faulty sensors).

Obviously, you want to check the normal stuff first. Low refrigerant, faulty high or low pressure sensors, blown fuse, bad relay, bad clutch, bad climate control unit in the dash...these are all potential things that could prevent the AC clutch from engaging. However, if all of those are good, you might have the following issue.

Symptoms:
No AC compressor clutch engagement
If powered and grounded directly to the battery, clutch functions normally
Multimeter shows you are getting 12v at the AC clutch plug when AC is selected on the dash and engine is running
If you send power directly to the terminal for the AC relay it would not engage, or would engage erratically. In my case if I wiggled around the wiring harness it would kick on and off.

What turned out to by my issue was a partially broken ground wire at location G105. I have attached an image of it's location from the service manual. The ground for the AC clutch runs into the wiring harness that feeds the fuel injectors on the driver's side of the engine, and terminates at the G105 location.


Here is a video I made for my dad to show him where to look on my brother's truck
https://photos.app.goo.gl/Jdh5WdKVTGgshx7x5

Hope this is helpful for someone. This was a real headscratcher for me for a little while and am happy to have it functioning again.