Turned my A/C on the other day and the only vent it was coming out of was the dash defroster vents. Doesn't matter what I select, everything comes out the defroster vents or heater vents at my feet. The center vent system doesn't work. Any ideas?

 

blend door stuck closed maybe a vacuum hose came off

 

As mentioned above, most likely it's a vacuum problem. Make sure all the lines are ok for the hvac systyem.

 

Hey, i bumped this because i'm having the same problem and i'm not sure what vacuum lines to check, nor do i think thats my problem.... see if anyone can help.
I removed my blower because i had sucked up a plastic bag. When i removed it, the blender flap was in the vent position (blocking the defrost passage way) which seemed normal to me. when i started the ac back up, it went to the defrost position and stays that way no matter what setting it's on.