The center vents always stay closed no matter what buttons I push (or modes I am in) I just wanted them to open in the AC position. The AC works but only comes out of the sides and defrost. Now that the center vent is "propped" open I get some air flow (although not great, but at least some)through the center as well. I am just wondering if this is doing any sort of harm having the flap propped open? Thanks