GMC Repair: Airflow Problem, fan speed control, vacuum hoses

Question
Hi, I have a 1996 GMC Jimmy and the airflow only comes out of the defrost no matter what selection i choose. everything else works fine (temperature control, fan speed control) I've read a few others that the vacuum hoses are the most likely culprit. where are the vacuum hoses located? or is there any diagram that could help me find them for my vehicle?
Thanks!

Answer
hi
The vacuum line attaches to manifold vacuum on the right (passenger side) of engine. It goes along the firewall towards the drivers side and attaches to a vacuum storage tank, mounted on the hood on the left (drivers side) close to the hinge. (looks like a black softball).It comes out of storage tank and into dash and then attaches to the rear of the A/C controller. The controller then splits the vacuum to whatever actuator it needs to to deliver airflow to your setting.
I would think you'll find the leak either along the firewall, or at the storage tank.
I hope this helps.
Just advise from experience.
Good Luck
Paul