The engine in a vehicle gets hot when it is running because of friction caused by its internal moving parts. While the engine oil helps to reduce the friction, the cooling system circulates coolant (also known as antifreeze) through the engine to manage the temperature. Once the coolant leaves the engine, it cycles through the radiator, where wafer-like ribbons, or “fins,” of aluminum absorb the heat and allow it to dissipate in the air that passes through the radiator. The engine’s cooling fan helps to draw a higher volume of air through the radiator, especially when the car is at a standstill, so that the coolant temperature decreases. For the most part, electric cooling fans are controlled by the same computer that controls the engine. However, in some engines, the fans are turned on and off by a temperature-sensitive switch mounted in either the radiator or elsewhere in the cooling system.