I recently completed an install of a Ford Taurus electric fan on my 78 and I struggled pulling together any coherent guidance. There are threads out there, but they generally have more questions than answers. I'm posting this to give a bit of a how-to and share what I learned.

First off - finding the right fan. I used a fan assembly from a 1995 Taurus 3.8L. Just under $100 from Rock Auto.
https://www.rockauto.com/en/catalog/...+assembly,2181





This is a dual-speed unit with a 3-wire connector. One pin is +12v for high speed, one pin is +12v for low speed, and the third pin is for ground. The connector pin-out, looking into the male plug on the fan unit is:




Unfortunately, while the male connector is still manufactured, the female (that would be on the Taurus's wiring harness) has been obsolete for about 15 years. The only two options are either to find a Taurus in a junkyard and cut the connector off and splice it in, or cut off the stock connector on the fan and install something that is still made. I opted for the latter. I used a Delphi 3-wire power connector available on Amazon:


I wired all three pins even though I'm only intending to use the low speed for now. For a control relay I used a 40A-rated relay also available on Amazon. This is a 5-pack, and each relay comes with a pig-tailed plug for easy installation.


The relay is set up with the hot coming directly off the alternator output (fused at 40A), and running through the normally open contact to the fan. The coil is wired directly to +12v switched power, and the ground side of the coil is sent to a temperature switch. Amazon has a selection of these switches. The one I used is a 200F-on 185F-off setpoint. I had to get one with a 3/8" to 1/2" adapter to fit the stock thermostat housing. Since I don't intend to use the dual-speed function I'm only installing a single switch. There is a BMW dual-setpoint switch out there that could be used to control a second relay for the high speed function but I found the low speed works just fine to keep temperatures where they belong.


Here's a quick-and-dirty wiring diagram. I grounded the fan to the ground screw on the back of the alternator to minimize the circuit resistance.


More to come.

 

Mounting the fan:

First off, here's the engine bay with the mechanical fan, shroud, and radiator removed. Notice the stock shroud clips are still there at the bottom of the radiator support.



I used 2" x 1/8" aluminum bar to fabricate the mounting structure. I'm running an aftermarket aluminum radiator so my stock upper hold-downs don't fit very well. I removed the rubber inserts from those to give me a place to bolt the upper bar using 1/4-20 bolts:


For the actual radiator, I bent two strips at 90 degree angles using my bench vise and a hammer - if you put a little pressure on the bar and then tap with the hammer you can get a decent quality bend, and I didn't notice any serious cracking in the aluminum with the thickness only being 1/8".



This was then drilled and tapped to match the stock holes on the Taurus fan shroud. Its a mix of 1/4", 3/8" and 5/16" bolts. There's no bolt hole in the lower right corner of the shroud, but there is a nice little flat area. I used that to drill a hole for a #6-32 screw.


Lower right - #6-32 bolt

Upper right - 3/8" bolt

Right side bracket positioning

 

I don't have any photos of the left side bracket during fabrication, unfortunately. Somehow I missed that. There's a photo below that shows it installed in the engine bay.

Here's the initial fit-up. The bottom of the brackets slot into the stock radiator shroud clip. The 1/8" thickness gives a tight, solid fit. The biggest problem I encountered is right here - there is negative clearance between the fan shroud and the front sway bar. It was difficult to get the brackets to slot into the clips rather than going next to the radiator into the bottom of the core support, and when I did it flexed the shroud enough that I was getting contact between the shroud and the blades. I ended up having to clearance the fan shroud with my grinder by about 1/8" to make space for the sway bar.


It took some careful set-up and measuring to make sure the brackets were even, parallel, and held the fan at the right height. I tried to line up the top of the shroud with the top of the finned area on the radiator. Doing it over again, I would probably move it a little higher to avoid the sway bar interference. Once I had everything in the right place I riveted the vertical brackets to the horizontal support. In this picture you can also see the left-side support with a 5/16" bolt in the top and 1/4" bolt in the bottom. I repurposed the upper hold-down rubber pads in the bent corner of the bracket to act as a cushion to hold the radiator in place.

 

FInally, on to the electric. On the driver side fender of my car I had enough space to route one more wire loom. Here you can see the Delphi connector on the fan, the wiring jumping out at the alternator for the power, ground, and signal wire to the temperature switch, and the relay, which has since been tucked back behind the washer fluid reservoir.

I would recommend getting the crimp tool for the Delphi connector pins - I spent a long time being very careful with my manual crimpers getting that crimp done correctly without horking up the pin.




The white wire is the switched power going to the fuse box. I routed this through a firewall penetration just inboard of the brake booster that looks like it was designed for vacuum lines. There are three ports but my car only has two lines installed. The wire slipped through the third hole easily.





Underneath the dash, here you can see the wire exiting the penetration, tied off the the speedo cable to keep it out of my feet, and then plugged into the ACC port on the fuse box. For some reason these GM fuse boxes have exposed blade connectors on the front face - perfect for this application. I just installed a female blade connector on the wire and plugged it in. The ACC position is switched with the ignition key so when you shut the car off the fan turns off.



And last, the temperature switch. I removed the vacuum switch in the thermostat housing and installed my new switch there. This type of switch shorts the input to the housing when the setpoint is exceeded, which is why it needs to be on the ground side of the relay coil. The stock vacuum switch in this location is part of the A.I.R. system which has been defunct for quite a while on my car.




And that's all she wrote. Testing with the car idling in my garage, the fan will come on at the right temperature and takes about a minute to cool everything back down to the 'off' setpoint. The low speed setting hasn't had any detrimental effects on the alternator as of yet. I got about 0.2V less when the fan is running at the alternator output. Getting rid of the mechanical fan also makes the car sound nicer by removing the fan noise, and it even seems like the butt dyno is detecting a little more oomph at higher RPMs.