After scouring the internet for ford taurus fan wiring i finally came upon a decent solution. I can't take credit for the design but I will explain it the best I can here. I also will pose a few questions and options to you all.
Apparently Volvos of various years used dual speed electric fans that were managed by a nifty little all inclusive relay, sensor controller and power input.
here is the part with some of the wiring from the donor vehicle
I actually picked up two of them because they were cheap and I found them.
One came from a 1992 Volvo 960 and was found behind the passenger headlight
The other came from a 1997 Volvo 850 and was on top inside of the passenger side of the fan shroud.
Other than wiring colors they are exactly the same as far as I can tell. I imagine these can be found on a wide range of volvo vehicles. If they have an electric fan just follow the wires from the fan motor back about 2-3 feet and you should find the relay/controller/power box thingy.
looking at the picture on the far left you have a green and red heavy gauge wire that will go out to your fan motor. I believe they are the same gauge so to which fan is up to you. On the far right you have a heavy gauge wire that will go to a heavy duty (75a-80a relay) then to the battery and to a switched power source.
Now here is where the options appear. I have drawn out what I believe to be the two best options.
Option ones utilizes two temperature sensors one to control the low speed and one to control the high speed. The question I have is what temperature settings should be utilized? I don't believe their should be overlap as running both high and low speed motors at the same time would burn them out quickly. Should their be a temperature gap between the temperature probe ranges (ie. low on at 185, off at 165, high on at 210 off at 185)? With this option I would have a simple on/off rocker switch on the dash that when in normal operation would be in one position but by switching it would cut power to the relay. An LED would indicate that the fan has been overrode and are off.
Option two utilizes only one temperature probe and a 30 amp bosch relay with 87 and 87a terminals. The normally closed circuit would be attached to the temperature probe the normally open circuit would be attached to the high speed trigger/sensor wire. This relay would then be run to the cab where a 3 position switch would control it, (down=normal operation based on temp, middle=off with LED indicator, up=high speed fan)
In the middle you have two small gauge trigger wires that will go sensors (these are low draw)