95 Suburban A/C and Vent Control

I'm having problems with the A/C and vent control on my 95 Suburban. The suspect is the control unit in the dash but wanted some opinions before tearing the dash apart. These things work: fan speed control, temperature control, and rear window defrost button. These things don't work: vent control and A/C button. The air blows only on the floor. Any ideas would be appreciated via email to S_Gaulding@yahoo.com

Problem solved. I replaced the control unit in the dash and everything works again. Apparently this is a common problem ... the control units going bad. Thanks to everyone that offered suggestions and comments.