I want to incorporate a '90s model Taurus 2 speed fan in place of my stock fan. I have used this great fan successfully on another of my cars with a Volvo relay control system and BMW sensor in the upper radiator hose. The BMW sensor simply provides the grounds for the Volvo relay control and several different temperature selections are available. Both the Volvo relay control and BMW sensor can be purchased on eBay for approximately $40. The only wiring required to make this system work is a switched +12 volt, +12 volt battery and a good ground. The BMW sensor provides the grounds for the two speed control Volvo device. The problem I have at this time is incorporating fan control when the A/C is switched on. (My other application uses a separate fan for the A/C and that fan is controlled by the A/C trinary switch.) For this install, I would like to stay with only one fan to accomplish all of this but my problem is figuring out the proper wiring schematic to incorporate the A/C fan control. Any help would be appreciated.

 

If anyone is interested, this may be one way to approach the solution. Be aware if you use this, it may/will require some modification to make the installation the way you want. This should also work for two single speed fans and you may not want to use optional manual switches for fan control.
http://www.binderplanet.com/forums/i...how-to.133615/