AC vent ducting and warm drivers side air

Can anyone tell me where I might get diagrams for these damn ac ducts? My pain "99" 3.5 is always comming up with some little problem. I have central air and from the center vent I get frigid air from the right side and warm from the left, I would think that the center was fed by a single duct but maybe not. I'm at a loss right now. I got great help here with a blinker problem so I am back, HELP!