When does the engine radiator fan start running?

[DiDaniela]

The engine radiator fan starts running when the coolant temperature reaches approximately 80 to 90 degrees Celsius. The fan is installed behind the radiator and draws air from the front of the radiator when activated. The fan automatically turns on or off based on the coolant temperature, with the following operational requirements: 1. The fan motor draws high current during operation, requiring higher-grade wiring; 2. The fan rotates at high speed during operation, demanding advanced manufacturing processes. Engine radiator fans can be classified into: 1. Axial flow fan: Blades push air to flow in the same direction as the shaft; 2. Centrifugal fan: Blades push air to flow perpendicular to the shaft; 3. Mixed flow fan: Air intake follows the axial direction while exhaust follows a diagonal direction between axial and perpendicular axes; 4. Cross-flow fan: Generates large-area airflow with both intake and exhaust perpendicular to the axis.

[SanIsla]

I remember driving for decades, and I know best whether the engine fan is running or not. It usually starts up after being stuck in traffic or climbing a steep slope in summer, because the engine temperature soars to over 80 degrees then, and the fan is needed to blow air for cooling. The fan also often runs when the air conditioning is on, as the compressor generates heat and increases the load. A broken fan poses serious risks—the engine can overheat, get damaged, or even break down. That's why during regular maintenance, I always have the mechanic check the fan motor and sensors to ensure it kicks in when the temperature rises, preventing any mishaps on the road. Hearing the fan whirring in traffic tells me it's protecting my beloved car—this experience is crucial for an old driver like me.

[Sean]

When driving my new electric SUV, I noticed the fan is incredibly smart—it automatically activates when sensors detect high water temperature or the air conditioning is turned on, providing cooling. During daily city driving with long stops at red lights, it runs frequently to cool the engine and prevent overheating. The fan only operates when needed, saving fuel and extending engine life. The high-tech computer control system in modern cars ensures the fan responds quickly, and if the fan fails, the central display will pop up a warning to alert me. When climbing steep slopes, the fan spins at high speed to prevent the engine from overheating and getting damaged. I find this feature quite practical.

[BrookeLynn]

From a mechanical perspective, the cooling fan typically activates when the engine coolant temperature reaches around 90°C. It operates through sensor-controlled electrical power to the motor, which drives the fan blades for heat dissipation. When the air conditioning is turned on, the increased heat load from the compressor may trigger the fan to start spinning earlier. Common malfunctions include erratic fan operation or complete failure due to faulty temperature probes, potentially leading to engine overheating and cylinder damage. It's recommended to use a diagnostic tool to check the fan's voltage supply, ensuring proper operation to extend vehicle lifespan.