I believe the temperature cut-in for that vehicle for the electric aux fan is 107C and cut-out above 100C. Air conditioniong will also make the aux fan come on depending on pressure.

Mercedes designed this car so that below 95C without the A/C on, there should not be any fans doing anything to provide mass airflow through the radiator. It is supposed to reach at least 95C in traffic. This is what the engineers wanted it to do.

Your fan clutch is operating as it should. You got a brand new part that is functioning as it should. If, with the old fan clutch, it never even reached 90C, I would assume the old one was broken and cutting in too early, as a new part should not bahave like that.

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Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record