Power Steering Pump problems of the 1997 Volvo 850

Both vehicles are the same models and years, but one vehicle is a sedan, and the other is wagon, # yv1lw572xv2341959, while driving over large puddles water entered power steering belt, causing a loss of steering which could have resulted in a crash. It usually lasted up to 30 seconds before power steering was back to normal. Dealer could not determine the cause. Driving in rain or large puddles cause the belt to slip on the pulleys resulting in loss of power steering and warning lights on the dashboard coming on.