The vent doors inside the dash are moved by engine vacuum. Do they re-direct the air at all ?? If none of the adjustments are moving, then the vacuum hose from the engine is probably at fault; Could be cracked, unhooked, etc. If some work & some don't, then one or more of the door actuators could be stuck. For that, you'll have to crawl under the dash & look for the actuators, there are a couple, & see which one isn't moving.