Rear Window Wiper Washer Linkages problems of the 2007 Jeep Wrangler

The contact owns a 2007 Jeep Wrangler 4x4. On three occasions while driving 25mph, the snow froze the linkage on the vehicle and the wipers didn't operate normally. Snow also enters the heater ventilation screen at the base of the windshield, which is a closed chamber where the windshield wiper motor and the linkage is contained. The snow freezes into a solid mass where the linkage/ wipers will not work until you put some form of heat into the chamber to melt the ice. The rain also makes contact with the electrical components attached. The dealer was unable to duplicate the failure although they stated this failure has occurred in other vehicles. The manufacturer informed him to contact NHTSA. The failure mileage was 30. The current mileage was 2,100.