Nissan Repair: Overheating Problems, temperature gauge, electric fans

Question
Hi

Having problems with overheating. When aircon is on, electric fans operate normally, keeping engine temp normal. When aircon is not on fans do not operate at all, causing overheating. Have checked all relays, all ok and have replaced sensor near thermostat housing.
Have I missed another sensor or maybe a problem in the wiring? Crook earth perhaps?

Thanks in advance.

Answer
Juergen,

Either the wrong sensor was replaced.   Disconnect the one you replaced, start the car, and watch the temperature gauge, if it does not move you replaced the wrong one.  If it moves you replaced the correct one.  The temperature sensor is the most probable suspect since the same relays work the fans.  They are only grounded by information provided by the air conditioner or temperature sensor commanding the closing of the circuit.