Let’s briefly discuss whether the cooling fan in a car blows air inward or outward.
Category:
Industry Trends
Release time:
2021-03-22
About cars Cooling fan Should the airflow be directed inward or outward? Does everyone know about this? Today, let’s talk about the conditions under which a car’s cooling fan will start up.
The cooling fans currently installed in automobiles all use electronically controlled systems to quickly cool down the engine. In other words, when the engine temperature rises too high, the electronic control system activates the fan; once the temperature drops back to a safe level, the fan stops running. During operation, cooling fans switch between high-speed and low-speed modes to adapt to different engine conditions and ensure the engine runs smoothly.
Since today’s electronic fans all operate using electronically controlled modes, what factors can trigger the activation of an electronic fan? And how exactly does an electronic fan work?
There are two factors that trigger the activation of the electric fan: one is the engine coolant temperature, and the other is the refrigerant pressure in the air conditioning system. The operating principle is as follows: The engine coolant temperature sensor continuously transmits a coolant temperature signal to the engine control unit in real time. However, when the engine coolant temperature exceeds a certain threshold, the sensor sends a signal that activates the electric fan. As mentioned above, the control mechanism for the air conditioning refrigerant is similar to that for the coolant temperature, and the two systems do not interfere with each other. Under the condition that all relevant criteria are met, the electric fan will be activated.
If the electronic fan starts up immediately after you start the engine—without the air conditioner being turned on and with the engine temperature relatively low—this is abnormal. We recommend taking the vehicle to a repair shop for inspection. Now that we’ve discussed the underlying principle, let’s speculate on some likely causes. First, it could be that the engine coolant temperature sensor has malfunctioned. The sensor might be sending a signal indicating high water temperature, prompting the electronic fan to start up in an attempt to cool down the engine. If this phenomenon occurs when the air conditioner is on, it could be due to an issue with the refrigerant pressure signal being transmitted. Typically, using a specialized automotive diagnostic tool can help pinpoint the exact cause of the fault.
There’s also a very specific reason: a malfunction in the ABS wheel-speed sensor can cause the fan to spin at high speed. The underlying principle is this: When a car is traveling at high speed, it’s typically operating under heavy load, and the engine temperature is relatively high. To help cool down the engine, the fan spins at high speed. However, if the ABS wheel-speed sensor is damaged for some reason—even when the vehicle is moving very slowly or even stationary—the signal sent to the car’s computer will still indicate that the vehicle is traveling at high speed. As a result, the fan will activate and start spinning at high speed, regardless of the actual driving conditions.
As for the situation mentioned above, the author does not agree. To put it plainly, an ABS sensor is nothing more than a wheel-speed sensor—a device that transmits signals indicating the rotational speed of the wheels. How could such a sensor possibly trigger the electronic fan to start running? I’m utterly puzzled.
The electric fan blows air inward because, under normal driving conditions, cars move forward, and the airflow naturally flows from front to back across the vehicle body. If the electric fan were to blow air outward instead, wouldn't that create a contradiction? Crucially, the engine is located behind the electric fan—so if it’s not blowing air backward, where else could it possibly blow?
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