Models With A/C
WARNING: This page is about a different car, the 2004 Subaru Impreza. However, it is still accessible from the selected car via links, so may be relevant.
On models equipped with an air conditioning system, the ECM or ECM/TCM receives signals from the engine coolant temperature sensor, vehicle speed sensor and A/C switch, and based on these signals, the ECM controls the HIGH-LOW of the radiator main fan and sub fan.