Q: We hear some sort of sound coming from vents. Sometimes air comes out and other times no air will come out at all.

This is a brand new vehicle. The second week we had it we were driving for about two hours in warm weather when all of a sudden there was no air whatsoever coming out of any of the vents. We had to turn down the windows to cool off. When we stopped and re-started the vehicle everything was fine and air blew out of the vents like nothing happened. Things were ok until a couple weeks later the same thing happened except it was very cool outside and pouring rain. We couldn't get any air out at all so the windows fogged up and our feet got cold. Again it was on a longer trip so we were about two hours from home. When this happens we hear a low grating noise in the vents but no air. Last time we turned the climate control up to the maximum heat and after a couple minutes we could smell hot plastic so we just turned it all off. Took it to dealer yesterday and they said they can't find anything wrong! Aargh.

My car has 5000 miles.
My car has an automatic transmission.