Radiator fan: It is attached to the main engine's radiator and it is used to push fresh air through it.
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Under normal circumstances, the radiator can dissipate hear by itself, but when the engine is overexerted, it generates more heat and, at that moment, the electric fan must start working to help dissipate this heat. When the air conditioner is turned on, this system also begins working.
Overheating i changed the engine i removed the thermostat radiator is clean the water level is the same… still only the water pump and the mecanicien said the water pump is working properly (altima 2009 mileage 210K)