Here's another tip. My wife's 95 GL had the same problem with the air vents. It was a lever that came off of a vaccuum diaphragm under the driver's side dash. Put the seat back all the way, and lay on your back under the dash. Facing the bottom of the steering wheel, look to your left towards the center of the dash. You can see the diaphragm and a small vaccuum line attached to it. To help you identify the diaphragm, do the following: With the enginge running, emergency brake engaged, and the trans in neutral or park, get a helper to turn the air on and change the vent position selector knob. You will be able to see it changing position. You will also see the lever near the top of the diaphragm. It should clip onto a threaded plastic piece on the top of the diaphragm. You need to thread a new nut and washer on it to keep the lever in place, (can't remember the size). Hopefully this will help you out.
