I'm installing an electric fan and had planned to wire it to a two position switch in the cabin, but am wondering if I can save myself the trouble and use an existing factory temp sender/switch? Then maybe have an override in the dash so I can disable it for fording...

The fan I'm using is a Volvo (same model# as the much loved taurus) fan with a built in 2 speed relay (wires for hi/lo, when grounded the fan turns on).