In my explorations I discovered a small company called Delta Current Control Automotive Control Systems. Brian Baskin is the principal of the company. You can view great information about the company, their products and the technology on their website. Since the website provides the technical specifics, there’s no need to go into great detail in this article. Suffice it to say that the controller – a solid state digital piece with only 3 large-wire connections varies the current to the electric fan in order to control engine temperatures to within +/- 3F of your desired set point. Set points are available from around 165F up to 220F in approximately 7F degree increments. It is an amazing piece in terms of its precise control, its simple hookup and its ability to get the air movement you need for low speed cooling while minimizing wear and tear on the fan motors, the alternator and the charging system. And, you are not using any more alternator “hp” than you have to at any point in time. The system has special settings for under drive pulleys, and can be set up to be triggered by your a/c system as well.