Every now and then when the heat is pumping out of both sides (which I keep set at about 70 or a little higher), sometimes the drivers side top vents AND the foot vents will get freezing cold for no reason. They wont change at all, and since you can't shut the bottom vent, I practically loose heat. The passenger side is fine. I thought it was just the top vent doing it (which would probably be a motor or flap that broke), but this is the entire side. Really annoying - anyone else experience this?