Does the car fan start spinning as soon as the car is started?

[Toni]

Car fans do not start spinning immediately when the car is started; they only begin to rotate when the engine coolant reaches the required temperature. Below are the specific details about car cooling fans: 1. Automatic activation conditions: The radiator fan automatically turns on when the coolant temperature reaches 98°C. The car radiator fan activates automatically and cannot be manually controlled. It does not start at low temperatures, and operates at two speed levels for medium and high temperatures. 2. Medium and high-speed fan operation: Typically, the fan starts at medium speed at 95°C and switches to high speed at 105°C. When the coolant temperature reaches 95°C, the fan starts running at 1600 RPM, and when the temperature reaches 105°C, the fan speed increases to about 2400 RPM to enhance cooling efficiency.

[MacDylan]

I've been driving for 15 years and never seen the fan start spinning immediately after ignition. The main function of the car fan is cooling, and the engine coolant temperature is still very low right after startup, meaning there's no need for cooling. Normally, the fan only activates when the coolant reaches around 90°C, triggered by the thermostat switch. When using air conditioning in summer, the fan will also operate simultaneously with the AC compressor. However, some German car designs are more intelligent - they perform a brief self-check of the fan system during startup, which might cause a short humming sound that stops immediately. My suggestion is to observe the coolant temperature gauge position after a cold start next time - wait until the needle slowly rises to the middle zone before checking the fan status for more reliable observation.

[McVanessa]

The repair shop has handled too many similar inquiries. Modern vehicles are equipped with electronic control systems, and the fan activation is entirely determined by the onboard computer based on sensor data. During a cold start, the engine oil hasn't warmed up yet, and the coolant temperature is only around 20-30°C. Turning on the fan at this point would only waste battery power. Typically, it takes about five minutes of idling for the coolant to reach the optimal operating temperature range. Recently, while servicing a customer's old Jetta, we discovered that he mistakenly thought the fan not turning on immediately was a malfunction. In reality, it was due to an aging temperature sensor causing the fan to activate 3 minutes later than normal. It's best to develop the habit of checking whether the fan is running during warm-up.

[Rodrigues]

New drivers are often troubled by this detail. There are two key moments to pay attention to during actual vehicle use: first, when the engine temperature exceeds 90 degrees, the fan starts to cool down; second, pressing the AC switch will force the fan to operate. When driving an American pickup truck, I noticed that on a 40-degree scorching day, turning on the AC immediately after starting the engine caused the fan to whir loudly. However, as long as the AC compressor isn't working or the engine temperature is low, even after baking in the sun for two hours, the fan remains silent at startup. There's no need to worry about the fan not spinning when it should.