2002 Silverado hvac stuck

[Jhajek]

Okay For the past week I’ve been on forums and everything trying to get my defrost to work on my 02 Silverado 6.0l the mode door is working I stuck my head under the dash and watched the actuator work. I even pulled the mode door actuator off and I moved the levers and gears around under the dash I herd doors close and open but still no air flow through the defrost. I might just take it in so a shop can look at it but I wonder if you guys can help me first thanks a lot 

[davester]

Are you sure you are looking at the right actuator, as there are 3 of them?  I don't know offhand where it is...

 

And it's possible for the actuator to move, and even move the shaft of the door, but for it to not work right.  One test to do would be to take it out, plug in it's cable, and watch it when you turn on the truck.  It should turn all the way one way, stop, then turn all the way the other way and stop, then go to the right spot for whatever it's job is.  Sometimes the physical stop on the actuator gets worn away, and it keeps going way too far, and the computer controlling it eventually figures it out and stops trying to use the actuator (until you restart the vehicle, then it tries again).  If you don't replace the actuator when this happens, it can break or wear the shaft out, and then you also have to replace the door (which is a much more annoying thing to do).