Engine cooling system control apparatus

A cooling system control apparatus for controlling the temperature of cooling water in a water-cooled engine, wherein said water-cooled engine is mounted on an automobile equipped with a heating system which utilizes the engine cooling water as a heat source, and said heating system includes an air heating core, a blower fan for supplying the hot air heated by the heater core into a vehicle compartment, a motor for driving said blower fan, and a fan switch for switching ON and OFF the current to said motor, said cooling system control apparatus comprising:

• a radiator for cooling said engine cooling water;
• a motor-driven fan for supplying air to said radiator;
• an electrically controlled water pump for circulating said engine cooling water through an engine cooling system circuit including said radiator and through said heating system including said air heating core;
• an electrically controlled radiator shutter positioned to open and close an air inlet of said radiator;
• electrically controlled valve means for regulating the amount of said engine cooling water flowing to said radiator;
• a water temperature sensor for electrically detecting the temperature of said engine cooling water;
• means for detecting the operating condition of said blower fan of said heating system;
• and
• an electronic control unit for receiving electrical signals at least from said water temperature sensor and said blower fan operating condition detecting means to control the operation of said motor driven fan, said water pump, said radiator shutter, and said valve means in accordance with the temperature of said engine cooling water and the operating condition of said blower fan so that when said water temperature rises above a first reference temperature T.sub.1 or said blower fan of said heating system is in the operating condition, said water pump is operated, and when said water temperature rises above a second reference temperature T.sub.2 higher than said first reference temperature T.sub.1, said radiator shutter is operated to open the air inlet to said radiator, and at substantially said second reference temperature T.sub.2 said valve means opens a water passage to said radiator, and when said water temperature rises further exceeding a third reference temperature T.sub.3 higher than said second reference temperature T.sub.2, said motor driven fan is operated.