Well, after advising a lot of people on overheating, it happened to me today. The day was about 92 F (33C), and I run my AC. after getting on the freeway (well, I wouldn't call the Blue Route that, but it is) I noticed my 190d was running at 100C. That has never happened, even with the AC on since I had the new compressor put in. As I progressed the temp climbed to about 105 C on inclines and dropped to normal 95-98C on level and downhill. After turning off the AC, the temp was normal no matter how fast or hard I drove.
I have a 1 year old t-stat, radiator, expansion cap, and no obvious leaks, but about 3 weeks ago I had to add about a pint of coolant. It's possible, that the upper radiator hose is leaking in a stealthy way. I'll replace the hoses, flush the system, put in MB coolant, and report back
