Ac problems

I have a 05 Chevy tahoe. I'm having problems with ac . The ac and heater is on but not coming through when I am moving. My rear unit works fine. An solutions to what is going on? I also can hear the vents opening and closing when I hit the buttons. Have limited control also

Do you hear the blower running and does it change speeds when you move the speed selector switch? If not, check the fuse. If it only runs on or off, then the resistor pack is faulty. If nothing, it could be either the dash switch or the blower itself.