Cooling System: Description and Operation

DESCRIPTION
- The engine cooling system consists of a down-flow radiator which features high heat-dissipation performance, an electric motor fan, a water pump, a thermostat, and an engine coolant temperature sensor.
- The reserve tank is designed to eliminate the need for replenishing coolant.
- On models without an air conditioner, the ECM sends an ON or OFF switch signal to the radiator fan in response to signals from the engine coolant temperature sensor. On models with an air conditioner, the ECM sends ON or OFF switch signals to the radiator main fan and sub fan in response to signals from the engine coolant temperature sensor, vehicle speed sensor 2 and A/C switch.

OPERATION
This cooling system operates in three steps depending on the temperature of the engine coolant flowing through the cooling circuit.

1st Step ... With Thermostat Closed
At the engine coolant temperature of below 76°C (169°F), the thermostat remains closed and the engine coolant flows through the bypass and heater circuits. This permits the engine to warm up quickly.

2nd Step ... With Thermostat Opened
When the engine coolant temperature is above 76 - 80°C (169 - 176°F), the thermostat opens and the engine coolant flows through the radiator where it is cooled.

3rd Step ... With Radiator Fan Operating
When the engine coolant temperature rises above 95°C (203°F), the ECM sends ON signal to the radiator fan in response to signal from the engine coolant temperature sensor and the radiator fan rotates.