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 subfan 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 91 °C (196 °F) to the ECM, it causes the radiator fan (or fans) to operate.