When I turn on the a/c, air does come out of the defrost. It does not come out of the vents however. I've done some research and this is due to a vacuum leak? There is a missing vacuum line that connects to the top of the heater valve and I was wondering if that could be the source of my problems. If anyone could tell me what I need to replace it and where it's routed too would be extremely appreciated. There's also what appears to be a cut vacuum line behind the aftermarket stereo the last owner put in, which could also be a part of my issue. Thanks for your time.

 

I've included a color-coded diagram and a video link to a common repair for our thirdgens.