In most modern vehicles, the cooling fan is designed to turn on when the air conditioning (A/C) system is activated. The primary purpose of the cooling fan is to assist in cooling the engine coolant and the air conditioning condenser.
The cooling fan operates independently of the airflow passing through the radiator. It is not directly dependent on the flow of air passing by the radiator. Instead, it is controlled by various factors, including engine temperature, A/C system pressure, and signals from engine control modules or sensors.
When the A/C system is activated, the cooling fan is typically set to run at a higher speed than during normal engine operation. This helps dissipate the additional heat generated by the A/C condenser. The cooling fan's operation is based on signals received from temperature sensors, pressure sensors, or A/C system switches.
While the airflow passing through the radiator can contribute to cooling, it is not relied upon as the sole source of cooling for the engine or the A/C system. The cooling fan provides additional airflow to ensure optimal operating temperatures are maintained, especially during idle or low-speed driving conditions when natural airflow may be insufficient.
The cooling fan will continue to operate as long as the A/C system is on and the operating conditions (such as temperature or pressure) warrant its activation. Once the A/C system is turned off or the system reaches the desired temperature or pressure range, the cooling fan may continue running for a brief period to cool down any residual heat before automatically shutting off.
It's worth noting that specific vehicle models and manufacturers may have variations in the design and operation of cooling fans, so it's always advisable to consult the vehicle's owner manual or reach out to the manufacturer for precise information regarding your particular vehicle.