1986 buick regal problem

Hi Everbody, Here Goes-
I Just Purchased A 1986 Buick Regal With Believe It Or Not 6000 Original Miles. It Is Super Nice And Looks And Smells Brand New. My Problem Is, Is That When You Turn On The A/c Or The Vent It Comes Out The Defroster And Heater Vents. The Fan Works Excellent. I Assume It Is Because The Car Hasn't Been Driven A Whole Lot. Could It Be A Vacuum Leak, Or Some Kind Of Switch? If Anyone Has Any Advice As To What It Could Be I Would Appreciate It.
Thanks

get the glove box opened up and look up behind the radio. i "think" there is some kind of vacuum manifold up there, look for some vacuum hose going into a boxy looking thing. make sure all the hoses are connected. been a long time since i looked at one but i'm pretty sure it was on one of my regals. good luck, keith