all of sudden my air flow stop on windshield glass on 1998 Chevrolet Venture

all of sudden my air flow stop on windshield glass so i can't drive in rain. if i block (close)all vent then i get very low air flow in windshield. how can i fix it

by in Elmhurst, NY on March 20, 2013
2 answers 2 comments
ANSWER by , March 21, 2013
Check for any broken vacume lines that supply vacume to HVAC controls. Vacume is supplied from engine intake manifold.
COMMENT by , March 21, 2013
thanks a lot
ANSWER by , March 21, 2013
Sounds like selector switch not switching, will it switch from vent to floor and back? Anything fallen into defrost vent? Check ebay for control panel at a good price, if needed. No vacuum defalt should be defrost!
COMMENT by , March 21, 2013
thanks a lot