System Outline
WARNING: This page is about a different car, the 2008 Lexus LS 600hL. However, it is still accessible from the selected car via links, so may be relevant.
It is a system designed to maintain a balance between effective cooling and air-conditioning performance, in which the cooling fan controller controls the cooling fan motor speed continuously, based on signals from the ECM. These signals are the result of an analysis of the water temperature, air conditioner coolant pressure, engine speed and vehicle speed signals.