Engine coolant is circulated through the coils to keep the stuff hot and effective in freezing weather. 170F seems a little hot though, like it could hurt if you got hit with a spritz.
I seem to recall spilling hot coffee while driving cost McDonalds some bucks, so the idea you could try cleaning the windshield off while stopped in traffic and spatter some on a pedestrian and end up in court is a little troubling. Kind of hard to hit the same spot as the McDonald's hot coffee got, but in an eye might generate some jury sympathy.
If you find out more, please post it, as water that hot seems potentially dangerous. Jim
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)