4.3L Sonoma 99 AC/Heater Blend Air Door

I did'nt use heat since many weeks and and blend air door don't seem work because i get cool air only at any position (cold on AC and fresh on heat). I checked for proper liquid level and the hoses at at heater are hot. Can somebody explain me where the blend air door is located? I looked under the dash and behind glove box to find 4 vacuum control but none seem to be the blend air door. Help would be appreciate !

I have the same problem and question in my 98 sonoma. Any response would be greatly appreciated.

The hot/cold blend door is operated electrially via a servo motor and is located on the passenger side nearer the transmision hump. For diagnosis, first check the dash switch for worn contacts before tearing apart the dash to get to the servo motor. Good luck!

Oops, old post...hope this closes it.