This should be covred under warranty through PNA,
I would first suggest exhausting your resources trying to get them to fix it. I've pulled dash-assemblies out several times and it isn't a fun job to say the least.
I'd call the dash-job about an 8-hour trip. . . . But maybe a little more if you're going to play search and rescue on that noise.
My best guess is going to be something found inside the vent assembly which is the biggest unit found in the dash. This unit will need to be removed to be checked, it can be as simple as a screw just sliding in there or a blade not seated correctly....
-Eli


