Technical Articles

Installing a TCI Thematic-Controlled Auxiliary Cooling Fan

-- by Paul.

Have you ever walked by a late-model car or truck in a parking lot on a VERY hot day and heard the little electric radiator cooling fan running shortly after it's engine has been shut off? Have you ever thought that you would like to have one of those neat little fans to help keep your Bronco's engine compartment cool after you shut it off? Well, now you can!


You have probably not seen this TCI Slim Line fan and thematic controller advertised before as an auxiliary radiator cooling fan. Well, That's because  it's not. This fan was designed for remote-mounted transmission coolers where no outside air is available, not for radiators. Also, the thematic controller is a little-know optional kit to go along with the fan. But guess what? It works even better as a radiator cooling fan than most of the "real" auxiliary fans marketed specifically for this purpose! Not only that, if you look at the picture above, the 12" TCI fan almost looks like it's a factory installation from Ford!


When you combine the TCI 12" fan (P/N 827000) with the TCI Adjustable Thermostatic Control Switch (P/N 826500), you can setup an auxiliary cooling fan that will kick on whenever your engine reaches a certain temperature, will kick on (regardless of temperature) whenever you turn on your A/C, and will continue to run (if you wire it properly) after your engine is shut off to help cool your Bronco's engine compartment. Below are two wiring diagrams I created to demonstrate how to properly wire the fan and the thermostatic switch in to your Bronco. Figure 1 shows how to wire both the fan and the switch on a Bronco with A/C. Figure 2 show how to wire just the fan itself using simply a toggle switch to activate the fan should you decide that you don't need the fancy automatic thermostatic control system.


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Fig. 1

Wiring Diagram w/

switch on Broncos


Fig. 2

Wiring Diagram w/

Aux. Fan only


If you choose to install just the TCI 12" fan as in Figure 2, you will have to provide the toggle switch because it is not included with the fan. If you choose to install the TCI fan and the switch as in Figure 1, you will only need to buy a little extra wire to complete the installation because everything else is included in the kit.


After studying the wiring diagrams above, take a look at the photos below (Fig 3-7) to get an idea of how the fan and the thematic switch will look after the installation.


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Fig. 3

Thematic Switch installed on Core Support. Note temperature adjusting screw on the right side of the switch.

Fig. 4

Orange Wire from +12 V connector on switch to 20A fuse on AUX fuse box (Switch comes w/ 20A inline fuse)

Fig. 5

Red Wire from IGN. Coil connector on switch to "constant" BAT terminal on solenoid

Fig. 6

Blue Wire from Fan & Black wire from "Ground" connector on switch to NEG BAT terminal (Ground) 

Fig. 7

View of fan looking down from under hood. This give you an idea of how slim this TCI fan is!


There are just a few things to keep in mind when you install this kit on your Bronco.


  • The location of the switch -- I mounted my switch on the front of the core support for easy access to the adjusting screw. If you go off-road with your Bronco, you may want to mount the switch behind the core support so that it will be better protected from water. I have installed a coolant recovery system on my Bronco that prevented me from doing so

  • Setting the temperature -- You will have to play around a little with the temperature settings to get it right. It's best to adjust the settings in summer when the extra cooling is needed most.

  • Running the Fan after Ignition is shut off -- If you choose to wire your Bronco like I did so that the fan will continue to run after the vehicle is shutoff until the radiator cools down then you may want to make sure you install a VERY good battery in your truck. I have had my fan run for twenty minutes after shutting off the engine on a 100+ degree day. You can adjust the temperature setting down a little if you don't want your fan to run that long.

  • Installing the temperature probe -- TCI recommends inserting the temperature probe about 3" or 4" directly under the upper radiator hose inlet.

  • Installing just the fan -- If you prefer, you can always install just the fan to help cool your Bronco (as in Fig. 2). If you do, you will have to buy a toggle switch capable of handling AT LEAST 25 Amps. I would install a 30 Amp switch just be safe.


So, how does it work? Fantastic. This is a VERY powerful fan. In fact, if it works so well that my engine is almost completely cooled down after just 30 minutes. When I turn on the A/C and the fan kicks in while driving down the road, I can actually see the temperature gauge drop even on a 100+ degree day!


How much does all this cost? Well, the 12" Fan (P/N 827000) cost right at $56.00 and the thermatic switch kit (P/N 826500) cost right at $75.00 for a total of around $131.00.g


Paul's Product Score -- I give the TCI fan and thematic switch a 9.5. It could have easily scored a perfect 10, however, the wire to the temperature probe is very short which limits where you can install the switch and the kit did not come with quite enough wire to do the job (although I expected this).