Dodge Caravan A/C blows through defroster but not vents?

[kathy]

We have a 91 dodge caravan and the A/C works good. The only problem is it won't blow through the vents. It will only blow through the defroster. We have checked the valve to make sure it was open correctly, but don't know what else to do.

[tlworkroom]

Either it's the valve itself not moving or else it's the control knob or lever on dashboard. There is a wire which is attached to the knob/lever so that when you move the lever, between heater, vent, a/c, and defroster, a flap or valve is moved to divert the air flow thru the correct tubes.
So it's possible that the wire is loose. But that would also mean that the other air sources wouldn't work. Meaning if you move it to heater, it will only bow thru defroster, too.

But then it may be the wire down to the valve is somehow hanging up. The wire has to be strong enough to push and pull the flap so that it moves either way. But that's the only things I know that could cause the problem.

Oh, wait, it's possible---highly unlikely----but it's possible that the tubes have become disconnected inside the dash. In other words, the tubes for the airflow thru the vents have become disconnected and so the air doesn't blow thru them.

However, can you get air out of the vents at all? Move the lever to 'vent' and see if you get air. If you do, then something else is weirdly wrong. But if you can't get any air flow thru "vent" setting, then it's probably the flap isn't moving to change the air flow.
Put it on heater setting and see if you get air flow to the bottom. You don't have to have the temp on hot, just keep it on cool temp. See if the air flows thru bottom where you'd normally get hot air in winter, and if you don't then it's the flap that's not moving to change the airflow. It's actually a common problem.

[Joe w]

your door for the vents is not opening

[tomblindewey]

more likely you just have a broken vacuum line under the hood check at the entry point at the fire wall on the pass. side . and also on the model you have i think also at the brake booster the vac. line connects there. hope this helps.