Chrysler Repair: no heat, dash vents, auto temp

Question
I have a 1987 chry 5th ave. The a/c works very good. It's just that i get no heat. The inlet and out let hoses that lead to the heater core get hot but no hot air comes through the vents.The car does have auto temp control to blend the a/c and heat to get a certain temps. Could the heater core be blocked and if so how do you unblock it. All vacum hoses are connected and a tight seat.It goes from dash vents to floor vents with no problems. There is a vacum operated valve on the inlet hose. Should it be opened or closed when the heater is on? I don't feel any vacum with the heat on or the a/c on.

Answer
The vacuum to the heater contol valve should be 0 for heat and applied vacuum for ac.I'm pretty sure that you have an electric motor that moves the blend air door.I believe its on the top of the hvac box.To be honest with you its been a long time since I worked on one of those.And I don't have any books on that on hand.You might want to try disconnecting the battery to see if it will recalibrate itself.


Its really funny how these things work.Today I get to work,and whats waiting for me? A 87 5th ave. So I checked the blend air door is controled by a motor.You can roll up the windows and move the contol back and forth slowly.See if you can head the motor moving.