Wow, these seems like exactly what is going on with my 2020 1500 RST.. The noise is like a circling metal washer just going around and around and around.. I have tried the A/c on and off, but never messed with the vent closed/open configurations to get it to stop.. Or haven't noticed it when they have been closed open.. But this would make a lot of sense as the sound is def coming from the front left area of the drivers side... I thought it was a Hub or break issue..