Last night it was 70 degrees F. outside, I was 45 minutes from home and traveling at 70mph when I heard the slap of a breaking belt and the dash lights came on. I knew it was at least the alt. belt, so I pulled to the side of the road, left the car running and got out to check under the hood. One belt (alt) was missing and the p/s belt was stuck behid the waterpump pulley. The electric fan was not running. I got back in the car, turned the heat to max, and shut off any unneeded electrical items and the a/c, intending to drive home thinking the electric fan would keep the thing cool. I hadn't driven half a mile before the temp gauge started up and quickly went into the red. I pulled over again and shut off the engine. The electric fan was now running and the p/s belt was intact so I rolled it over the water pump pulley and went on my merry way. My question is: Why did the car overheat? Usually if you have good airflow through the radiator you can travel quite a while before overheating. By the way, these were non-volvo belts with only 30K on them. I've put hundreds of thousands of miles on Volvos without a belt breaking, so I'm back to buying genuine Volvo belts.