Once (recently) when I suspected cooling problems, I disconnected the A/C fan sensor on my 300E near the thermostat to get the fans to kick on high constantly. It DID cool the car somewhat, but I felt that I would eventually burn out the fans if I kept that up every day.
So now with the Texas temps hitting 100F and above, I certainly do not panic when the gauge gets close to 100C when in town or in slow gridlock. It actually creeps even higher if I make a stop and then return to the car a few minutes later (to about 105 C).
This is all normal, especially with the A/C running.
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car