why dont the engine fan come on when the engine heatup
could be the fan motor is bad or the coolant sensor what engine size? ,try hitting the fan motor and check if works , if does it needs new fan motor
See if turning on the AC activates the radiator fan. If not, the fan or relay for the fan is bad. If the radiator fan does turn on with the AC, it is most likely the coolant temperature sensor, which if I'm not mistaken is on the bottom side of the thermostat housing on the right side of the engine.
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