I seem to have the opposite problem from the norm. I cannot get air to blow out the defrost vents. I know I have no leaks and I'm guessing the control must work as the mode and recirculation doors work. Does anyone know the vacuum line color for the blend door so I can check it and where in the dash is the actuator located?

 

with the key on, engine off, I get good strong airflow through the vents. start it up, and it goes away, even with the defrost button pushed. would this mean my control module is bad?

 

in most cases its just the resistor that went bad, its not to expensive and fairly easy to fix. Grand caravans have this issue alot

 

resistor? I thought this was a vacuum and cable operated system. isn't the only electrical stuff for the illumination?

 

yes most of it is but the controls still need some type of resistor or gauge to to tell what setting is needed or used. Some of the vacuum lines can just wear out after time and collapse. Its easy to take out the dash face plate and check behind the controls I would start with that