[busboy4]

Hi
I have a '96 too. Now, there is an early production version (mine) that only has a rear fan speed control, and a late production version where the front control also directs where the rear air flows - up/down. Either way the airflow to the floor or ceiling in the rear is controlled by a damper driven by a "vacuum motor". The damper defaults (no vacuum) to the heat/ floor position. So, you likely are not getting vacuum to the rear actuator when you select an A/c function, or it has failed.

Does your front air selector work normally - can you control whether air goes to the panel/defrost/floor up front? If so, you have good vacuum all the way to the front panel selector. So, then you are loosing vacuum along the line to the rear actuator.

I would start at the rear actuator located in the side panel under the rear air control. The vacuum actuator is located on the fan housing and should be a bulb shaped device with an actuator arm extending into the fan housing to move the damper. On the early production models my manual says the vacuum line should be green to the actuator. On a late production model that line should be white. You can test that actuator by removing the vacuum line and applying suction - I have a nice hand vacuum pump that is great for jobs like this - or how ever else you can improvise. If you can move it with vacuum, and it will hold position with vacuum applied (doesn't leak) then it is ok and you likely have a leak along that green/white line that should run into the floor, along the driver door floor area and up to the vacuum block above and to the right of the accelerator. You should be able to open the vacuum block such that you can test a specific vacuum line - they are all different colors.

Let me know what you find. I could try and scan or fax a manual page to you if that might help.