Took the Jeep back to the second dealer today. They found the refrigerant leak and replaced a line, just a few hours total. Unfortunately, before I shut down after a 20 minute drive, I heard the whistling sound from the front again.
Going to drive for a while to see how reproducible this one is. We had the sound for months without a breakdown so I'm in no hurry to drag the Jeep back 40 minutes out of my way to the dealership again
. I did send the service adviser a note about the problem.