heat problems

i have a 95 grand am,2.3 quad eng.it has 120000 miles and still runs great.my problem is the the heat only blows through the vents.there is no problem in the temp. settings.i replaced the mode control switch and that didn't change nothing.i noticed vacuim lines on the mode control but i can't see where they hook up to.theres no cables,so i guess its vacium controled.can anyone give me advice on what to do so i can have a defrost and floor setting.thanks jeffreyjjm

welcome jeffreyjjm . Does sound like a vacum leak, on the back are several hoses, check and make sure none are cracked or just pulled out/loose. But it is vacum controled.