My 2008 chevy uplander rear a/c upper vents blows no air.. the only controls the van has is on the dash for the rear a/c.. what could be my problem.. thank you

SOURCE: There is no air flow

You need part GM Part number 89018675 or ACDelco 15-73596. The Mode Selector Actuator. What happens is the part is a CHEAP part POORLY designed and when it goes to turn the flaps inside the HVAC unit its the plastic gear slips instead of turning the flap!!!

Just to forward you you might want a deal to install this art for you unless your good at fixing your own vehicle, because you need SMALL sockets and a lot of patience to get this part in!!!

The part is ALMOST directly above the steering shaft for your steering wheel, so theres a lot you got to remove before you will even see them!!!

I only recommend you to have a dealer put this part in for you, unless you have your own service manual!!

Because there is 5 of these darn things and if you pick the wrong one you will have to do it all over again!!!

3 on the Drivers side and 2 on the Passengers side!!

But replacing this part SHOULD solve all your problems!! AS it did for me and i was having the same issues as you have described!!

SOURCE: Heat wont blow through heater or defroster vents

The door in the heater box is most likely stuck. It is located under the dash on the passenger side

SOURCE: Heat wont blow through heater or defroster vents

common problem, check under dash by the gas pedal if control arms are muving went selecting from ac to heat cuz this it is the control for the vents to go from ac to heat and to defrost.

SOURCE: 97 Chevy Tahoe dash vents not working

ck for vaccum leaks at engine comparment small plastic lines

SOURCE: No air blowing from the dash vents

sounds like you have a vacuum problem