Welcome to the site. I pulled my vents. (You can also go on you tube to get a visual on how to pull them.) Once they are removed, look for the pivot point where the vents move. I cut small pieces of plastic to fit in the opening where the pivot point are located. Worked fine for me.
Once you pull them and see how they operate, you may have some other ideas of how to fix your problem. If you can't fix it, PM me and I will pull one of mines and send you a photo.
2006 GT, Strut Tower Brace, Gas Hood Struts, FR Intake Plenum cover, Metal Fuse Box cover, Moroso brake reservoir cover, Rear shock tower brace, Front Bumper Lip Spoiler, JVC DVD Head unit w/ back-up camera, satellite Radio and USB input, 2 - 12" sub-woofers, 4 - 6"x8" speakers, 2 - 6.5" speakers to replace the door subs, 3 amplifiers, LED lights under the hood and in the trunk, chrome e-handle on parking brake handle, chrome cup holder trim, and trunk lid cover with running pony emblem.