Chevrolet Repair: no defrosters, vacuum leak, defrosters

Question
1980 chevy scottsdale pu iam getting no air coming through my defroster going to the windshield it is coming good through vents and the arm on the control goes all the way over to defrost iam getting plenty of air from my blower motor to all other vents but with winter coming on i will not be able to keep my windshield clean thank you for any help

Answer
Hello Don, I haven't worked on a 1980 in a long time. I'm not sure if the heater doors work off vacuum or a cable. Does it switch to the heater? If not then I would look for a vacuum leak at the intake manifold. If it is cable operated just look under the dash while you move the lever and maybe you can see the problem.

Sorry I can't be more help on this one

Mark