A worn AC belt idler pulley may cause the AC belt to roll over in the pulleys or come off completely.Google+
Car Problem Reports
Chrysler Concorde Worn AC belt idler pulley may cause belt to come off
Chrysler Concorde Problem
Visitor, 1999 Chrysler Concorde
Found belt rolled over in AC pulley groove (engine was not running at time), it was broken.
Been getting squeal every once in a while while driving, when it squeals, you can feel it hold back slightly.