Just in case I am NOT the last person in the world to think of this.....

If you get to the point in your "A/C inop" diagnosis, that you are thinking the little "A/C" button on the control panel just doesn't work, switch the mode controller to Defrost. Is the A/C on now? If it is, you have just eliminated a few other possibilities. (e.g. ambient temp, engine temp, WOT-kill, evap temp, hi/low pressure)

This obviously won't work on every car in the world, but it's free to try it. Heck, I might even try it FIRST next time. :-)

Geoff from Hawaii