I have a 2003 Blazer that is giving me fits recently. The heater core was leaking, so I replaced the heater core over the weekend. What a pain in the butt!

I am now having and issue with changing the vents, etc. via the climate control head (I believe that's the proper term). When I move the dial around to head, feet, defrost, etc. I get no reaction at all. The air continues to flow out of all the vents (the best I can tell). It turns off and on, there's no change in the direction of air flow. I pulled the controller out and looked at all the connections and everything looks good. I dropped the glovebox and look at the connections there, and everything looks good.

Everything as far as I can tell everything is hooked back up the way it was prior to the heater core replacement. Obviously I am missing something, but I don't know what.

Thanks in advance for any help that's provided.

 

Just had the exact same problem with my 2003 blazer. I was stuck on the face vents, no matter what I switched to. Turned out some vaccum switch with the 4wd went bad, which is supposedly a known problem. This also caused the transfer case to engage causing loss of gas milage. Anyway, that breaking somehow pulled transmission fluid into the heating systems vaccum lines and took out 3 of 4 actuator/motors. Also took out the heating switch on the dash. Mechanic showed me the switch and motors and you could plainly see the tranny fluid. Maybe you can start at the dash switch and look for the fluid. Good luck, was a costly fix for me.