In some cars the fan is driven by a separate electric motor and only blows air past the radiator when the engine gets very hot or when the car is not moving. However, when the cooling system works, the cooled liquid goes back to the engine to move more heat out.

If the engine is air-cooled, the heat moves out of the cylinders through fins in the engine wall. Fans and the movement of the car continue blowing the heat off the fins.

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