Can an evaporator rework?

What is your question?

I was told my evaporator was bad as I was only getting hot air, too expensive to fix now so I went to pick up my car and it's working just fine now blowing cold air, can an evaporator work on and off before it breaks?

What makes this problem better or worse?

Not sure if evaporator is really broken or in it's something else and shop misdiagnosed it