A coupla ways to go about it... first is to use two temperature switches... one for the low speed/low temp and the other high speed/high temp. The links in the Tech Info Compilation provide background.


The other is to use an actual (electronic/digital) controller like that offered by Hayden and others.


DIGITAL FAN CONTROLLER


Hayden - 2-Speed 2-Fan Controller


Personally, I would stay away from any that uses a probe stuck between the cooling fins... notoriously inaccurate.


Visit Hollister Road for a one-stop shop or at least to get an understanding of what is possible: https://www.hollisterroad.com/browse?category=5098

 

These are the diagrams I used for mine. I did 2 fans independently wired to a relay in case one burns out. I also had a switch in the cab. Easy install following these instructions. Good luck.

http://www.davebarton.com/pdf/coolingfandiagrams.pdf

 

I working on a little book about e-fans, so this post caught my eye. With the Lincoln/cougar/mustang fans that you mentioned, there are many types. Some, from the 90's, have two wires. They are variable speed fans, speed controlled by the computer. Some are two speed, which have 3 wires. I would only say to avoid the 93--96 fans as they are slow, 1100rpm on low. Whereas the 97--98 fans spin 1800rpm on low.

If you want to use the variable speed units, use a Delta Current Control control unit. But there's a wait time, and about $100 price tag. Or... contact The Fan Man, and get a Spal controller for less, but DCC has a better reputation.

A Taurus or Volvo fan (Ford owned Volvo) would work fine for you as well.

Here is a link for the least expensive route, the one I use: This video shows the volvo fan and the controller ($15 from a j/y). The following links are rather boring since the photos are now dead, due to photobucket now wanting to charge to host them.

http://www.rx7club.com/showthread.php?t=839089
http://www.nastyz28.com/forum/showthread.php?t=200028

http://www.pirate4x4.com/forum/gener...ication-2.html

The Lincoln/cougar/mustang fan uses 26-28 amps on low, and has a 37-40 amp spike at start up.

The quality of the wiring (10g) and relays is very important for these fans, and for your electric system. It's not fun to fry wires. Make sure you have about a 130 amp alternator to run the run and the rest of your vehicle.

 

Thanks for the links/video. I've done a fair amount of research since then but the progress on the '75 is nil. Too much other stuff going on.


On another note, I have talked to Brian Baskin of DCC on the phone. He's seems to be a really nice guy. I know he gets a bad rap but mainly just due to the wait time. As of when I called and talked to him, 3 weeks which is nothing to me.