On a trip from northern Alberta to southern Saskatchewan, about 800 miles each way, the air conditioner on our 1992 GM van then about 8 years old failed suddenly. I drove in the heat for hours. Stopped to fill up with gas and struck up a conversation with the guy at the next pump. I was checking under the hood for something obvious without any luck. The guy said he was a mechanic and asked a few questions, then pulled out a small wrench and tapped on a valve several times. Suddenly the air conditioner worked!
It worked until it was 20 years old then gradually the cooling power faded away. A retired mechanic and refrigerator tech friend pumped out the old freon and put in two cans of new stuff. It is still working well!
I think the lesson is to find a knowledgeable mechanic.