I have had a similar problem with my Peugeot 206 Type 1 Digital air conditioner for many months now.
On some really hot days, if I leave my car in the hot sun and then start the ac; the ac starts and then cuts-off. Then the heater blows really hot-air, which continues to blow even if you then switch ac & heater off.
The problem is worse when I leave the car parked in the sun with the front-side higher than the back side. And once it starts, it only goes away after the car has cooled down for about an hour.
Have had it checked at the dealers without much success, the problem comes back on some really hot days. BTW. I live near Dubai, where the temp. sometimes touches 52C...
Raza
July 2008