General Information: General Description

When the ambient air temperature is warm, or when the airflow across the engine is low, the engine coolant temperature can become hot. If the coolant temperature becomes too hot, it is possible that the engine could be damaged. The purpose of activating the engine compartment ventilation fan is to help reduce the engine coolant temperature to a level that is not threatening to engine performance, while maintaining the air conditioning system pressure at safe levels. The electric fan is responsible for providing air movement around the engine coolant radiator. The amount of air movement from the fan is controlled based on the vehicle speed, coolant temperature, A/C pressure status, A/C switch request status, and A/C clutch state. A duty cycle is determined based on these input parameters. This duty cycle corresponds to fan speed, which correlates to the amount of air movement provided by the fan. The increased air movement enhances the heat exchanger function of the radiator in the confined space of the engine-compartment, thereby reducing the engine coolant temperature more quickly.