2001 Tarus AC runs hot & cold

My daughter’s has a 2001 Taurus and the air conditioning just had freon added. The air will be cold and then turn hot and then if you let it run awhile it turns cold again. The shop has it at the moment but can’t find the problem.

Does it really turn hot, instead of just not-cooling? If so, you likely have a blend-door or electronic control problem.

BTW, Freon is R-12. The 2001 would take R-134a. Surely, they used R-134a?

You are right, I should have said it stop cooling the air. They did put in R-134a, that I’m sure of. Thank you for the for your help.