Cooling System: Description and Operation

General
^ The engine cooling system consists of a down-flow radiator which features high heat-dissipation performance, an electric-motor-driven fan, a water pump, a thermostat, and an engine coolant temperature sensor.
^ The reservoir tank is designed to eliminate the need for replenishing coolant.
^ The ECM controls the operation of the radiator main fan and sub fan depending on the signals from the engine coolant temperature sensor, vehicle speed sensor and A/C switch.

Cooling Circuits
The cooling system operates in three different phases depending on the temperature of the engine coolant.





^ 1st phase (thermostat closed) When the engine coolant temperature is below 76°C (169°F), the thermostat remains closed. The coolant flows through the bypass and heater circuits. This permits the engine to warm up quickly.
^ 2nd phase (thermostat open) When the engine coolant temperature is above 76° - 80°C (169° - 176°F), the thermostat opens. The coolant flows through the radiator where it is cooled.
^ 3rd phase (thermostat open and radiator fan operating) When the engine coolant temperature sensor sends a signal indicating a temperature above 95°C (203°F) to the ECM, it causes the radiator fan (or fans) to operate.