A/C Vents Not working properly..?

My 2003 Impala A/C - Heater - Defrost vents always seem to remain OPEN at the same time. Moving the dial that is supposed to change them does not good.

IT is summertime here and over 100 degrees each day...my A/C system works, but the air is blowing from ALL vents and so the car is not cooling down properly....

Has anyone had this issue...and if so....how can it be fixed....?

Thanks
MV:screwy:

If you've recently worked on or near the battery, check the vacuum supply line that runs from the intake to the firewall. It is common for this vacuum line to be accidentally damaged when working on the battery. There is a rubber junction near/behind the washer fluid jug that may have become disconnected also.