Dash vents will not blow

Ive got the dash 1/2 way out now,I really just want a quick fix.If i could get the flap to stay open i would live with that.jus need to know how to get down in there and what to look for.OK now(about 2 hours later),theres this sliver disc looking thing that has vacum lines that appear to be a send/return type thing.NEED all the help i can get.its hot down here!!!

what year of car

its a 1985