1. The coolant temperature sensor is faulty. The coolant temperature sensor is responsible for sending a signal to the engine control unit (ECU) when the engine reaches a certain temperature. When the ECU receives this signal, it turns on the cooling fan. If the coolant temperature sensor is faulty, it may not be sending the correct signal to the ECU, which could prevent the cooling fan from turning on.
2. The cooling fan relay is faulty. The cooling fan relay is responsible for supplying power to the cooling fan. If the cooling fan relay is faulty, it may not be able to supply power to the cooling fan, which would prevent it from turning on.
3. The cooling fan motor is faulty. If the cooling fan motor is faulty, it may not be able to turn on, even if the coolant temperature sensor and cooling fan relay are working properly.
To troubleshoot the problem, you can:
1. Check the coolant level. If the coolant level is low, it can cause the engine to overheat and the cooling fan to turn on.
2. Check the coolant temperature sensor. You can do this by disconnecting the sensor from the wiring harness and grounding the wire to the sensor terminal. If the cooling fan turns on, the sensor is faulty and needs to be replaced.
3. Check the cooling fan relay. You can do this by disconnecting the relay from the wiring harness and jumping the terminals. If the cooling fan turns on, the relay is faulty and needs to be replaced.
4. Check the cooling fan motor. You can do this by applying 12 volts directly to the motor. If the motor does not turn on, it is faulty and needs to be replaced.
If you are not comfortable troubleshooting the problem yourself, you can take your car to a qualified mechanic for diagnosis and repair.
