I am having a problem with my 2002 Blazer, no matter what setting the air blows out of the dash vents. I have checked out the problem and it seems to be the switch in the dash. Looking at it further it seems like all 3 switches are part of one unit. Where would be the best place to find one of these. Thanks

 

I would doubt that it is the switch in the dash actually. Have you checked for proper vacuum supply to the switch? Most of the doors in the HVAC system are vacuum operated.

 

Yes i have checked the doors with a hand held pump/gauge. When I move the switch threw the different positions I can hear it leak.

 

Mine was stuck on vent when I bought it, I ended up finding the door inside the heater box was broken off the pivot, When you switched the door the pivot would move and make it look like the door was switching when it actually wasn't, took me some time but I figured it out by removing the vacuum actuator by the gas pedal and turned the door by hand and it turned VERY easy, removed dash and heater box disassembled heater box installed the new $20 door and all working after 6 hours labor and a case off cold ones

 

Would have been good to put in the original post. It is very common to have a vacuum leak under the hood and have the symptoms you reported to a 't' which is why I mentioned what I did.

As far as where to get the vacuum controls, a junkyard would be where I'd go first. They don't typically go bad. You might want to pop off the dash bezel and remove your controls and see if it isn't something simple like a cover plate popped off it's clips or something that could be glued back in place for a free or almost free fix.

 

You checked the vacuum source also, right? The actuators inside the dash might work fine when you test them individually, but if the vacuum line coming into the cab isn't supplying enough vacuum to the switch, the actuators can't do their jobs.

 

Yes, I have good vacuum coming to the switch.