1996 Plymouth Voyager Plymouth Grand Voyager serpentine bel

Air Conditioning problem
1996 Plymouth Voyager 6 cyl Two Wheel Drive Automatic

My mother-in-law took her 1996 Plymouth Grand Voyager minivan in to get the AC repaired and for an oil change/fluid check/etc. On the short drive back to her home, the serpentine belt came off, the temperature gauge spiked, and the vehicle lost power steering. We had it towed back to the mechanic to be checked.

Questions: 1) Was the serpentine belt removed or loosened to fix the AC? Specifically to install a new drier.
2) Is it possible to tell whether the service technicians made a mistake in re-installing the belt or if it was just "coincidence"?

I have read that serpentine belts on this minivan come off in going through puddles or snow drifts, but the weather was perfect during the drive (no rain, no puddles, etc.). Thanks very much for any information you can offer.