1998 Ford Escort Fan not working??

Hi there, the radiator cooling fan appears to have stopped working. I ran 12volts direct to the fan and the fan worked. I checked the fuses and all ok. . Driving from cold the engine warms up. As it heats up there is a sudden drop in the temperature guage, possibly the thermostat opening. The engine then gets hoter and hoter. The temp guage shows normal but rising. When the fan was operational, the temp was never in the normal mark only in the white section of the guage prior to normal. From reading I believe there is two sensors on the water pump or thermostat housing. My thoughts are cooling sensor or sensors faulty and possibly repplace the thermostat. Can you confirm my diagnosis?
Also can you please tell me what the sensor is that is located on the radiator hose? Your response would be much appreciated.