air conditioning temp control

I have a 94 GrandPrix 3.1L and my a/c is stuck blowing HOT air. It started after I was driving one day and moved the temperature control knob to hot and then back to cold. Unfortunately it never went back to cold. It is stuck on full blown hot. My climate control unit has three round knobs. One for fan, temp, and one to select which vents are used. I am thinking that it is the temp control knob/switch that is bad because it used to have some resistance when you turned the know, almost like little clicks for the different positions, however now it rotates extremely freely and just blows hot no matter where it is positioned. The actual knob is not stripped, the shaft the knob fits on is turning just not doing anything. Does anyone have any ideas on how to resolve the issue. Do you think it is the temp control switch or possibly some door actuator? Does anyone know how to remove the climate control panel and is the individual switch replaceable or does the whole panel have to be replaced?

Thanks in advance,
Jack