I don't know if mine was the same problem:
coming home in Rome from a weekend in Austria, a 528 miles trip.
Here is a record hot summer: on highway I travelled with costant outside temp of 102 F.
No problems when I did the outward journey. During the round trip, after 200 miles, no cold air flowed from the vent. I heard the vent engine running at the maximum, but no air flow. I tried to shut down the A/C, commuting from auto to manual, without result. Setting manually the vent speed, cause the display bars varying correctly, the vent noise going louder or quiter, but still no air flow. The cabin become really hot, in the maeantime outside temp raised to 106F, and I was really worried for my two pets on rear seats. After 20 miles driveng in such a suffering situation, I drove in the first gas station and stopped the car, going out tho breathe (as far as you can breathe at 106F). After 5 minutes, I started the car and all went all right.
No more problems until home.
It seems like something "hunged" in the A/C control unit. This car is like a PC: if something hungs, just shutdown and power on again ?