Chevrolet Repair: 1989 Celbrity, chevy celebrity, vacuum line

Question
My Chevy Celebrity will not throw air through the windshield defrost vents.  I can move the switch from a/c to defrost but nothing happens.  I have checked the vacuum under the dash.  When I remove the vacuum air will change front dash vents to windshield vents.  What could be happening and what could I do?

Answer
It sounds like you have a bad switch. By removing the vacuum you are letting the flappers fall where they choose. There really isnt a way to check the switch other to replace it. If it's not the switch then there is a vacuum line somewhere in there you can't see without removing the dash.