HVAC distribution servo

00 Silverado 1500 Z71.. Does anyone know the location of the HVAC distribution servo?? I found the air blend servo under dash. Only getting air blowing out of Defrost. I switched the head unit and got same result. Also tried the reset as suggested by Jcat, neither one worked. Any help would be Appreciated...

No need to post a 2nd tread on the same topic. Stay with the original and we'll do the best we can to get you going in the right direction.