Need Help!

1996 GMC 4x4 K1500 Suburban
Air will not blow out the front vents, goes from floor to defrost and rear air works fine. All the lights and switches seem to work accept air vents. The switch motor actuator by the gas pedal changes, I removed it and manually moved it, no change same results, the outside air motor actuator changes, and the temp mixer air flow motor actuator moves when you change temp. Is there another damper some where? This model doesn't seem to use vacuum at all with in the ...