my van had one in the thermostat housing.
wires run down the face of the front cover and linked up with the main loom..didnt notice any wiring.
fans kicked in and cut out fine...not sure what the thermostatic switch was from though...
im not a fan of constant running fans..in winter it is a bad idea cos the water in the radiator doesnt get hot enough to open the thermostat,so once the engine water is hot it opens then it gets a hit of cold water and closes again,and continually does it..
also you have a higher chance of the coolant freezing, i know this from experience..my rotor van had a constant fan,and the radiator froze over while idling for a bit,then driving into ashburton in winter... cracked housings anyone?????