1992 Ford Tempo where can i fing the fan relay sensor

the relay is in front near battery and upper radiator hose on 4 cyl cars. the sensor is on the thermostat cover i beleive. some people just hot wire their fan to run off a switch or continuosly when car runs. iv'e done that before. i used a regular house wall switch. does seem funny for fan to quit if engine is getting hotter? maybe it's starting to fail?