$hawn

I'v noticed that not very much air comes out from the middle dash vents, positions 1 and 2 on the blower switch **** results in very little air and 3 and 4 are still barley enough to feel. Actually most of the air that comes out is from the defrost vent and the floor vents. I'v checked the vacume check valve and it's fine. What else could it be the problem? Thanks.

94Z28WP

The vent/ac/defrost selector is operated by vacuum lines going to three or four(can't remember) different vacuum actuators on the airbox under the dash... The vacuum operates doors to direct air to different vents... Sounds like one of the lines is leaking or maybe disconnected from the actuator... Or possibly the vacuum isn't getting to the dash controller from the check valve... I had to replace my airbox a while back and I belive the actuator for the dash vents is at the rear of the airbox(someone correct me if I'm wrong)... Get down on the floorboard on the drivers side and you'll see two of the actuators on the box which sits ontop of the trans hump... The other is right behind it at the rear... What I'd do is start the car and turn the selector to vent and remove the line and feel for vacuum... You might have to wet your finger to feel it since it's a light vacuum... If you can't feel vacuum, you'll know either that line is leaking or the line coming from the check valve to the dash controller is leaking.

Joe Bellman

The line that runs between the vacumme tank and check valve may have cracked or broke.
If this is broken, don't waste time looking at the local parts stores, you won't find it. I tried 5 in my area before I went to the dealer. Tell them to order part number: 12124134

Check the valve and all three lines in this picture
http://shbox.com/1/vac_check_valve.jpg
here is the tank located under the car.
http://shbox.com/1/vacuum_tank.jpg

shoebox

Definitely sounds like a vacuum problem. Check the vacuum.

$hawn

None of the vacuume lines are cracked in any of the parts that are visable, but it is possible that theres a crack in some part thats in the plastic convuluted tubing, guess i'll have to check those out. Thanks guys.

shoebox

Ya gotta test them. Just eyeballing them is not gonna do it.