Which coolant sensor(s) complete the fan circuit so the Aux fan turns on? the one on the Thermostat housing? or the ones in the side of the head?

AND

I'm installing an electric fan, and ditching the belt driven fan, is the 100*c closing temp on that cooling switch too hot for the engine to be reaching on a regular, but not neccessarily frequent basis?

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RIP: 80 300SD
RIP: 79 450SEL
2002 E430 4matic (212,000km)
2002 ML500 'sport'

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