Get your head under the steering column and have a look see if the vacuum actuators are working when you shift the selectors. If not, then it's a vacuum problem, if they move and nothing changes, then it's your blend door lever.
My vacuum was poor, but when I looked closer my blend door levers were full of dust and crap, and after a quick clean and test the vacuum seemed adequate enough to shift them in reasonable time.
Although I think I just popped my face vent one again..... Apparently even a 1" decking screw and gorilla glue isn't strong enough to fix it