I don't think all MB's got a coolant temp sensor to turn on the aux fan on. I think the sensor you are looking at is for the A/C drier temp, and turns the aux fan on when the A/C refrigerant gets over something like 105*F degrees.

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1998 Mercedes E300TD

1983 Mercedes 240D Turbo, 131bar injectors, Cosworth intercooler and 63' Ford Falcon radiator, Ardic Parking heater, Headlight wipers, Best 38.6mpg.

1973 Saab 96 Rally Car, 1.8l V4 with all the race bits