will not switch from heat to ac

Does the compressor clutch engage? Most likely, you have a leak and are out of refrigerant. Possibly a bad pressure cut off switch.(easily visible with 2 wires plugged into it. The controls on a GS are a lot simpler than the LS, but I doubt if that's it.

I just had my car in the shop. They wanted to take the dashboard apart. I had already spent almost a thousand dollars on other things that needed fixing. The mechanic did hit something and I got my A/C. Now it's only heat. I really don't want to spend any more money on the car if I can. I am a snowbird in Florida and I can't afford another car. I guess I will have to try tapping it. I am a woman (93). If I can't get it going, I will try a friend.

Sometimes it can be fixed by taking out the glove compartment, otherwise, pull the dash. It's a blend door servo thats bad, or no vacuum going to the controls (easy)