What is the problem if the car cooling fan keeps running?
3 Answers
It is normal for the car cooling fan to keep running. Here are the detailed reasons: Fan delay shutdown is for cooling: When the engine is running, the temperature distribution in the entire water channel is not uniform, and there are local high-temperature spots. When the water pump stops running, these heat cannot be dissipated, so the fan delays shutdown to cool down, which is a normal phenomenon. The electric fan is controlled by sensors: Although the car is turned off, the temperature has not yet dropped. The electric fan is controlled by sensors. Sometimes in summer, when the car is parked in the sun, the electric fan will rotate even if the car is not running, as long as the temperature reaches a certain degree. This situation is normal. If you don't want it to rotate, you can turn on the ignition switch after turning off the car, but do not start the engine, just connect the power supply, and the electric fan will automatically turn off.
With over a decade of driving experience, I can say that a constantly running fan is usually caused by a stuck thermostat. The thermostat acts like a valve controlling coolant flow—if it fails and gets stuck in the open position, the system keeps thinking the engine is overheating, so the fan keeps spinning nonstop. This issue is common in summer, especially in older cars where the thermostat may corrode and cause trouble. Not only that, but a continuously running fan drains the battery quickly, making it harder to start the car after a few days, and it can also lead to higher coolant temperatures, increasing engine strain. For routine checks, start by inspecting the coolant level—if it's low, there might be a leak that needs fixing. Regularly replacing the coolant helps prevent corrosion and extends the thermostat's lifespan. If you spot the problem, don’t delay—get a mechanic to replace it, and you’ll save yourself a lot of hassle.
I'm a car enthusiast who enjoys doing some repairs myself. A fan that won't stop running is usually a sign of a faulty coolant temperature sensor. When that little component fails, it sends false high-temperature signals to the ECU, which then commands the fan to run continuously. A simple method is to check the sensor's resistance with a multimeter - if the reading is off, it's time for a replacement. Sometimes the fan relay in the relay box gets stuck with burnt contacts; try removing it and tapping it to see if it can be restored. Last time my car's fan was running nonstop, I fixed it in 10 minutes by replacing the sensor. Additionally, a short circuit in the fan control wiring could also cause continuous operation - check for loose wire connections. Prolonged issues can drain the battery and lead to more expensive repairs, but those with some mechanical skills can handle it themselves.
