It does seem as though a 103 with a properly-operating and maintained coolant system does not overheat. If it routinely reaches 105, there's an underlying problem, probably in the coolant system, and not in the air flow system. Blaming the 105C sensor isn't the answer, although reducing that trigger point with a modified resistor might make sense if the vehicle is routinely used for towing. Otherwise, I would look elsewhere for the fix to an overheating problem.

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1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't