Originally posted by walpoleb
By center button, do you mean the "auto" button for fan speed?
I believe Paul was referring to the "auto" button on the horizontal row of buttons, not the fan speed button (although this too should be on the "auto" setting). This is the center button. The one to its immediate right is the "economy" button which turns off the AC compressor.
Personally I'd bet you have a stuck air door which is keeping your car constantly in the recirculation mode. Do you hear anything when you do push the recirc. button? (That's the switch with the circle of arrows.) You should hear a vacuum sound and the sound of the door moving. If you don't, it would mean the door is stuck in the recirc. position.