One problem related to windshield wiper/washer has been reported for the 1998 Mercedes Benz ML320. The most recently reported issues are listed below.
In temperatures below 20 degrees the windshield washer fluid freezes up, even with DE-icer additive added to the system. When dirt is kicked up from a preceding automobile, you cannot clean off the windows, this leads to impossible visibility. Pulling off the road every 5 minutes to rectify this problem is not always easy to do. I'm 5ft. And its also hard to reach the window to clean it off. Several calls were placed for assistance, but I was told that the nozzles are not heated and not protected to keep the component parts from freezing. I almost hit a pedestrian since it was hard to see through the window. Driving like this all winter will be impossible.