[yorkie_chris]

Disconnect the sensor. Turn ignition on with engine off. Short across the connector on the loom side. The fan should run.

Then dump the coolant and remove the sensor. Or just remove the sensor and lose the bit of coolant out of the rad.
Put it in a pan of oil and heat it up with a thermometer in there and a resistance meter connected, or better yet a test light.

It should close the circuit (light the lamp, or show low resistance) at 96 deg... and go back to open circuit (infinite resistance) at 91.