When I replaced the radiator fan it would not come on. I called the local nissan dealer and they told me to change the sensor which I did. It still did not come on after letting the engine warm up so I unplugged it while the engine was running to check the connection.
When I plugged it back in it started to work. Now it works whenever the motor is running;hot or cold. I should not say hot because it doesn't warm up now.