I own a 1989 Trans Am Turbo 20th Annaversary Indy Pace Car. There is a vacuum leak at the AC control panal in the dash. The leak is evident with the control in the "OFF" position. I've determined that the leak is at the vacuum control valve. I installed a new valve, however, the leak continues (new valve also defective?). In looking at the color code of the vacuum hose rounting in the 1989 Shop Manual, it is obvious that the hose routing in my car does not agree with the diagram in the manual (red, orange and purple out of diagram position). Is it possible that the turbo car has a different routing? It appears that the vacuum source is the purple hose. Any help is appreciated.