Description & Operation: Notes

The engine cooling system consists of a cross-flow radiator (a down-flow radiator in the Impreza) which features high heat-dissipation performance, an electric cooling fan, a water pump, a thermostat, and a coolant temperature sensor (thermometer). The reserve coolant tank is designed to eliminate the need for replenishing coolant.

The electric coolant fan is controlled by the Electronic Control Module (ECM). 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 (thermometer). On models with an air conditioner, the ECM sends ON or OFF, and LO (low) or HI (high) switch signals to the radiator main fan and sub fan in response to signals from the engine coolant temperature sensor (thermometer), vehicle speed sensor 2, and A/C switch.