another EASY test...

go buy some resistors in verying resistance., unplug your harness from the sensor and connect the resistors across the 2 holes on the harness.

This will give a high/low ohm value to the car computer, (high/low depends on your resistor) and your fan should now adjust to STOP, LOW, MEDIUM or HIGH.

What resistors to buy, again, do a search for the table.