System Outline
WARNING: This page is about a different car, the 2008 Lexus GS 450h. However, it is still accessible from the selected car via links, so may be relevant.
This system is designed to maintain a balance between cooling and air-conditioning performance, in which the cooling fan ECU controls the cooling fan motor speed continuously, based on signals from the engine control module that are result of arithmetic processing of the water temperature, air conditioner coolant pressure, engine speed and vehicle speed signals.