I have had this situation happen twice, a year apart, but still odd that the same thing happened. I have a 1996 Ford Taurus with 53,000 miles. It was a hand-me-down from my grandmother. She barely used it over the years and so when the car was given to me it only had 43,000 miles on it. We picked it up in Texas and drove it California in 2010. Along the way, as we drove through the hot Arizona sun with the air conditioning blazing, we turned off the highway to get a hotel. When I turned right into the hotel parking lot the car turned off. No warning at all. All the lights on the dash were now on, but the engine had quit. The air was still blowing. After sitting for a few minutes, the car started right back up. After that, no other problems. The car was driven to LA and then up to San Francisco. A lot of miles for the car given that it had barely been driven in the last 10+ years. After a year of being driven regularly in Northern California, on a hot afternoon with the air conditioning on and after pulling off the freeway to get gas, I turned right into the gas station and the car again stopped working. All lights on the dashboard lit up, radio and air conditioning still working. After sitting for a few minutes, the car again started and no problems since.
I am unsure what would cause this particular problem and what to expect if I were to take it to a mechanic. Does anyone have any insight? Thank you.