Bobertbarker

First of all, if there is another thread on this same subject, I apologize. I searched and didn't find one. I have a 1978 280z Black Pearl LE, and I'm having a problem with the AC duct system. Air comes out of the vents on the console and on the far sides, but not out of the defrost or floor vents. I have a feeling that the vacuum flaps are stuck shut somewhere in the routing, but it could obviously be another issue. I can add pictures tomorrow if necessary, and any help is greatly appreciated. Thanks in advance.