I can't find a picture. The GM service manual doesn't make it easy to find either, its in the wiring diagram ( download/file.php?id=1733
) as evaporator temperature sensor. The only clue to where it is is in the instructions for replacing the evaporator core (the AC radiator thing inside the HVAC box, with the heater core and blower motor) The procedure says that after you remove the HVAC box, and then remove the evaporator from it, you can remove the temperature sensor from the wevaporator. but no picture Unfortunately, that process is extensive, involves draining the coolant, draining and collecting the refrigerant, taking apart most of the dash. Hope you don't have to go through that, but I doubt you'd be able to replace it without doing all of that.
I don't know how the wires to it are routed,but you might be able to find them at the ECU. The service manual does say that the temperature sensor should be about 2.2 K Ohms, but it doesn't give a temperature to resistance table. Still, if you can find the wires at the ECU, you could check for an open, a short, or a short to ground.
When the AC's running, does it get cold? Did you check for reasonable refrigerant pressure when its off and when running?
some folks look at all caps as "shouting", but I didn't take it that way.
Welcome to genvibe, good luck, if you get it fixed let us know what it took