Why does the Ford Focus fan keep running after the engine is turned off?
2 Answers
The reasons why the Ford Focus fan keeps running after the engine is turned off are as follows: 1. Water temperature sensor: The water temperature sensor is faulty, causing it to continuously record high water temperature signals, which are transmitted to the fan control computer, keeping the fan running. 2. Relay: The fan relay is malfunctioning, causing it not to disconnect in time after the engine is turned off, resulting in the battery continuously supplying power to the fan. Additional information: 1. Major circulation: Major circulation is generally used in summer to dissipate heat from the engine, so the cooling efficiency of major circulation is higher. During major circulation, the coolant flows through pipes to the cooling radiator at the front of the car, where the temperature is reduced by the fan next to the radiator before flowing back into the engine to carry away heat, thus completing the cooling cycle. 2. Minor circulation: Minor circulation is usually used in winter or when the outdoor temperature is not high to maintain the engine temperature. During minor circulation, the coolant circulates only within the engine and does not pass through the external cooling radiator. The pump applies pressure to the coolant, causing it to flow through the internal pipes of the engine, retaining the heat generated by the engine within the cylinder block to prevent the engine from losing temperature.
I also encountered this situation when I drove a Focus before. After parking and turning off the engine, the fan kept buzzing, which was really annoying. At first, I thought the car was broken, but later I found out it's a normal phenomenon. This happens because the engine may still be hot after shutdown, and the fan continues to run to help cool it down and prevent overheating. Especially when using the air conditioner in summer, the compressor may still have residual pressure, so the fan runs a bit longer to dissipate the excess heat. As long as it doesn’t last more than a few minutes, it’s fine. But if it runs for too long, say over ten minutes without stopping, then you should check if there’s an issue with the temperature sensor or a battery circuit fault. Next time you encounter this, pay attention to how long it lasts. If it persists for an extended period, go to a repair shop immediately to avoid draining the battery and getting stranded on the road. Additionally, the fan running after shutdown helps reduce engine damage and prolongs the car’s lifespan.
