Why does the car fan not turn when the water temperature is high?
2 Answers
Here are the reasons for high engine water temperature and the electronic fan not turning: 1. Water temperature sensor failure: Check if the engine water temperature sensor is faulty. A faulty water temperature sensor will prevent the ECU from receiving the signal of high engine water temperature. 2. Thermostat switch failure: Check if the engine thermostat switch is faulty. A faulty thermostat switch will prevent the electronic fan from turning on. 3. Electronic fan failure: Check if the engine electronic fan is faulty. Internal short circuits in the electronic fan will directly cause it to stop working. 4. Car ECU failure: Check the car ECU (central control computer board). The ECU is the 'brain' of the car. ECU failure can lead to various vehicle malfunctions.
I know this situation well. When the temperature gauge spikes but the fan doesn't kick in, nine times out of ten it's a cooling system issue. First check if the fan fuse is blown - it's in that little black box in the engine bay. Pull it out and hold it up to the light; if the filament's broken, replace it. If the fuse is good, chances are the fan motor is seized or burnt out. Try manually rotating the fan blades - if they're stiff, it's likely a bearing problem. Don't forget to check the relay near the fuse box too; swap in an identical one to test. Also, a faulty coolant temperature sensor can trick the ECU into not activating the fan - best to scan for trouble codes with an OBD scanner. The real headache is wiring issues - rodent damage or oxidized connectors can cause open circuits. Whatever you do, don't keep driving like this - you could warp the cylinder head and that's serious money.
