After spending almost 4 hours now with most of the components of the dash out (glove box door, radio, hvac controls, bezels) I have finally identified my stupid ventilation problem. Same problem as many others. Air comes out of the defroster and floor vents no matter what the setting on the control ****. Thanks to the forum I have INTENSELY gone through the vacuum system and lines to make sure all is well. Have tested lines right from the head that hooks to the back of the HVAC control. The vacuum is all there and there are no leaks. It's the damned actuator. I managed to be able to stick a screwdriver through a small slot and reach the actuator that the blue vacuum line goes to. This one controls the flow to either the front vents or the defroster vents. It was sorta working til a few days ago. The air would come out of the front vents but would switch to the defroster upon accelaration. Then switch back when I let off. It had been doing that as long as I've had the truck. Even replaced the vacuum check valve below the ball under the hood and replaced lines but still wasn't able to remedy that problem. Well a couple of days ago I was heading up over the overpass in town and had to punch it to get around someone. The engine downshifted and revved high, of course the air switched to the defroster vents....and it never came back. I think at that point the actuator went south. It does not move now. I think the vacuum seal on the actuator is busted and now it does nothing. My biggest gripe is that I can't get to it. I have been reading the forums and I just do NOT have the kind of time to totally disassemble the dash (one guy said like 17 hours if you're lucky) to get to the *^*%$ thing! WHY do they do this??? WHY does GM bury these stupid things like this behind a dash where you can't access them by removing a few things. And who's brilliant idea was it to use vacuum to do all of this anyway? Seriously folks, I've had older cars, foreign cars that just use cables to pull the doors open and shut. What the hell is wrong with that? At least you wouldn't have these stupid actuators to deal with and vacuum hoses and all that junk. Believe me if I could even GET CLOSE ENOUGH to the thing I would probably tie a string or a rod to it so I could just move the door manually to change the air to the vents. It is just SOOOOOOO buried back there and there is just no hope.
Sorry...I wanted to rant. Anyone else have a bad actuator and have some alternative suggestions or something? I'm at a loss and I don't know what to do now except just live with the air always coming out of the defrost and floor vents. Best I can tell I think there's another actuator that's bad as well....that one is buried on top of the left side of the heater core cover....like up and to the right of where the gas pedal cable comes in. If that one was working, then I should get ONLY upper defrost vents when I set the control to defrost....but I don't. It stays on floor and defroster vents. That actuator actually has two vacuum lines going to it so it turns on and off the floor vents and defroster vents......at least according to the diagrams I've found here in the forum. So....2 bad actuators and unless anyone has some other ideas I think I am pretty well screwed and would have to totally take the whole dash out to change them and there's just no way I can. I don't have that kind of time and certainly not hundreds of dollars to pay a mechanic to do it when I only spent $1300 on the vehicle.
So this is my last-ditch effort to grasp at straws. Anyone have any other ideas? I don't care as much about the floor vents....if there was just some way to get that other door working so that the air would come out of the front vents when I wanted it to.

Thanks for reading my rant

Michael n Wyoming