heater

Hi,We have a 2012 QX56 just ran out of warranty. My wife was driving it and smoke poured out of the vents. (it smelled like burning) She turned the heat off and the smoke stopped coming out of it. Does anyone have any ideas what I should look for to fix it?

After a few minutes when I turn off my car the fans appear to change zones and make a lot of noise doing so. Maybe closing when car not running? I'm guessing the 'gears' are slipping and trying to adjust from defrost zone, to floor zone, or possibly just closing up. It's not terrible as...