2003 impala Air conditioning selector switch stuck

My 2003 Impala dual climate air conditioning switch wont change to a different setting, it stays stuck with all ports open...floor,dash,defrost etc..no matter what setting i change it to...does anyone have an idea what might be wrong??? i would appreciate any help...thanks in adavance

2000 - 2003 they are vacuum based, so it could be theres no vacuum pressure making it to the selector leaving all the doors open, or the vacuum switch is busted?

Could take the dash off and remove the HVAC, and pull off the Purple/Orange connector (Circled in Blue in picture) and feel if you have vacuum.
http://i232.photobucket.com/albums/ee46/MaImpala/PIC_0108.jpg