Auto Air Conditioning & Heater Repair: vents, manifold vacuum, vacuum leak

Question
I have a 1993 s-10 and had the air worked on. its fully charged but the air only comes out the defroster and the floor board.  What can i do about this to make it come from the vents?  Thanks for your help..

Answer
Youre problem is possibly a vacuum leak, the inside air vent and defrost door actuator motors are moved by engine manifold vacuum- check all vac lines that lead to inside the cab starting at the engine trace the lines look for cracks or missing ports not connected if they seem ok start the engine turn blower on low listen at the control panel for hissing noise may be a bad vac control valve in the panel