Vent air coming through defroster and not vents

[Puettz]

Hello. I have a 2007 Gulfstream Crescendo 8356 and we noticed the dash air was going through the defroster and not the vents. I tried all the settings and the blower seems fine. After looking on YouTube, it sounds like the vacuum line might have a crack which makes the system default to the defroster for safety reasons. (It will keep the window clear). I do not know where to look for the vacuum line or any other tips that might help alleviate this problem. Any help would be very much appreciated. Thank you. There was a hose hanging in the fuse compartment at the front driver side compartment. I tried attaching to an opening but it did not help the issue. I will try and attach a picture.