fan controller question

I thought you had two fans, not a two speed fan.

If, in fact, you have a two speed fan, I ran across a simple set up that is working quite well for me on my truck. I am running the 2 speed Mark VIII fan controlled by a Volvo 2 speed relay that is actuated by a BMW dual thermo sender. I have about $50 into the control system. The BMW sender will send signal to turn fan on low when needed. If high speed is needed, the Volvo relay turns off low as the high speed comes on, essentially ramping it up without super high voltage spikes.

This is a link with a fairly complete run down on whats needed.
http://www.nastyz28.com/forum/archive/index.php/t-200028.html