Much to our surprise the man was very pleasant and professional. He examined our refrigerator from the outside, the roof vent and the inside. He determined that there is some insulation that gets sucked over the exhaust pipe causing the gas (which we use when not hooked to electricity) to shut down. It would have required unscrewing the entire vent assembly and securing the insulation and we didn't want to mess with the roof as it was raining. He assured us that there didn't seem to be any thing else wrong with the fridge. And he didn't charge us for his time.
We drove 430 miles today and the fridge worked fine 2/3 of the way. It wasn't until we had a strong cross wind that the fridge went out. My theory is that a cross wind causes the insulation to shift.