Chevrolet Repair: 1999 chev monte carlo LS, vacuum line, vacuum leak

Question
the air is blowing from the air conditioner only from the bottom and not the vents. I also just replaced the battery. the air worked fine before the battery was replace. in replaceing the battery could the person replacing the battery accidentally  disconnected something causing the air not to come out of the vents.

Answer
HI RICHARD, CHANGING THE BATTERY WOULD NOT HAVE ANY EFFECT ON THIS UNLESS THERE IS A VACUUM DASH POT AROUND THE BATTERY TRAY AREA. CK AND SEE IF THERE IS A ROUND BLACK VACUUM DASHPOT AROUND THE BATTERY AREA WITH VACUUM LINES GOING TO IT.IF THEY KNOCKED OFF A VACUUM LINE THIS WILL CAUSE THIS..!THIS SOUNDS LIKE EIHTER A VACUUM LINE FELL OFF OR BROKE OFF INSIDE OR OUTSIDE OF THE FIREWALL AREA.WHAT EVER CONTROLS THE VENT BLEND DOOR IS AT FAULT.I DONT KNOW IF THIS IS CONTROLLED BY VACUUM OR ELECTRICAL OPERATED DASH POT. GM CHANGED AROUND [2000 I THINK]. START YOUR CAR UP AND MOVE THE CONTROLS TO THE VENT POSITION,, DO YOU HEAR ANY KIND OF VACUUM LEAK UNDER THE DASH OR UNDER THE HOOD AREA ???  TURN THE RADIO OFF AND LISTEN REAL CAREFULL..IF SO FIND THE SOURCE OF THE LEAK AND REPAIR.. IF IT IS ELECTRICAL CONTROLLED MAY HAVE SOMETHING GOING ON WITH THE CONTROL HEAD...