"Mini Air Cooling Fan" various fan control types, control their own characteristics. Big car manufacturers what they need under different circumstances, and thus present a variety of types of control technologies coexist. A typical example is the US General series cars, such as Sail, Buick basic, Dongfeng Shenlong Picasso, Senna is also true of the cooling fan control which is integrated in the engine powertrain control module (PCM) in. Ambient temperature, the air conditioning compressor pressure, coolant temperature, intake air temperature sensor signal is sampled in order to control external power relays to control high and low two fans.