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The Boss
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Joined: Nov 2013
Location: Orlando, FL
Posts: 351
Drives: S13.5 Nissan 240sx (Fastback)

#1 - 02-12-2014, 12:59 AM.

Disclaimer: I am in no way responsible for you if something happens to you or your car after doing this modification. If you're not somewhat knowledgeable in wiring do not attempt this, find someone that knows what they are doing and learn from them. This is not a project for inexperienced individuals, period.

Tired of having to navigate around the bulky clutch fan? Don't like the outrageous price for a new fan clutch? Want to join the 21st century?

Whatever your reason may be, this will be a simple guide on how to make the switch to an electrical radiator fan setup.

- (2) Bosch style relays
- 12 AWG wire
- 16 AWG wire
- Toggle switch OR thermostatic switch (recommended)
- Butt connectors (12AWG) and (16AWG)
- Heat shrink
- (2) 30A Fuses
- Pack of female fuse connectors (12AWG)
- Pack of male fuse connectors (16AWG)
- Pack of ring terminals (12AWG) and (16AWG)
- Red threadlocker

- 10mm wrench
- 12mm wrench/ratchet
- Wire cutter / stripper
- Plyers
- Lighter or heat gun (heat shrink)

First start off by popping your hood and removing your battery entirely from the car.


Battery removed, clutch fan still in place for the time being.

At this point, time to remove any intake piping that is in the way of getting to the clutch fan and shroud. Once you do that, loosen the alternator belt a bit so when you remove the nuts from the pulley, it doesn't go flying off. No need to remove the alternator belt, just loosen it enough so there isn't a crazy amount of tension.

After you have done that, use a 10mm wrench and start removing the 10mm nuts holding on the clutch fan to the pulley. A ratcheting wrench works wonders here. Pull the fan out and remove it away from the vehicle. You can now put the 10mm nuts back onto the pulley. They should already have lock washers on them, if not you will need to find some. I also like to use a little red threadlocker on the threads to make sure it will not come flying off when driving.

Once you've tightened up the pulley, don't forget to tighten up your alternator belt. After that you can then pull the shroud out. You may have to struggle with it a little bit but with a little persuasion it will come out...


Look at all that space! Now is the perfect time to upgrade to a thicker aluminum radiator if you have one.

The next step will vary depending on what electric fans you decided to go with. I went with Altima fans from a 1997 model.

You will need to mount the radiator fans to the radiator as you see fit. I used a combination of screws and zip-ties to secure it. Whatever method you choose make sure the radiator fans have ZERO movement. They will need to be positioned about 1/2" from the radiator core itself and if they are flopping around while spinning they will damage your radiator and fan blades.

Once you've securely mounted the electric fans to the radiator, it's time to begin the wiring process. This can be done away from the car if you'd like but will require you to measure distances for wire cutting based on positioning within the engine bay. With that said, I would stay within the vicinity of the vehicle.

Here is the basic wiring schematic:


Let's start with wiring up the grounds for the electric fans.

You will want to find a good grounding location on the chassis for the fans. I found the perfect spot on my S13. Since I had removed emissions and the charcoal canister was no more, there are two perfect threaded bolt holes for a 10mm bolt.


This is where the charcoal canister bracket use to mount.

Once you have found your spot, measure the appropriate amount of 12 AWG wire (preferable in black) from the fan negative wire to the location you will ground to. Cut the wire and use a butt connector to connect it to your negative fan lead. I used butt connectors with heat shrink fitted over top. So once you make a good connection with the butt connector, slide down the appropriate sized heat shrink and shrink it down and around the connector to protect from the elements.

At the other end of the ground wire, crimp on some ring terminals so you can bolt the wire to the chassis with ease. Once I crimped the ring terminals on I also used heat shrink at the ends which can be seen in the picture above.

Now, the rest of the connections to be made will involve the two Bosch relays. One relay per fan. You will need to figure out where you will be mounting your relays so you can measure the appropriate length wires.

Next connection to be made will be from the fan's positive lead wire to the #30 terminal on the relay. Cut a 12 AWG wire long enough to reach from positive fan lead wire to the area where your relays are mounted. Again, the same procedure here. Use a butt connector to connect the fan lead to your newly cut wire. Crimp it down so its nice and tight and then slide some heat shrink over top of it and shrink it up nicely. At the other end of this connection you will hook up a female fuse connector for 12 AWG sizing. Crimp it down and slide over heat shrink on the tip to protect from any potential shorting out with other connections or chassis ground.

Rinse and repeat for the other fan, and connect it to the other relay's #30 terminal.

Now we need to configure the power supply to the relay.

Cut (2) 1 ft. pieces of 12 AWG wire. On one end, crimp on a ring terminal, and on the other end, crimp on a female fuse connector. Do this for both pieces. These wires will connect to the battery (+) terminal and run to the 30A fuses. Here are some pictures for reference...


Notice how I have not yet shrunk down the heat shrink for the female fuse connector side. You'll want to slide it ALL the way over to protect it from contacting the other terminal. Like so...


Completely protected.


One side of the fuse now plugged in. The ring terminal side of this wire will connect directly to your battery's positive terminal.

Now lets work on the other side of that fuse.

You will need to cut a 12 AWG wire the length from the 30A fuse to where your relays are. Do this twice, one for each relay. Follow the same procedures as you have been, on one end you will crimp a female fuse connector that will connect to the 30A fuse, and on the other end strip down some wire for a butt connector. Feed the wire through the butt connector and crimp it down. Remember, all the steps during this process you will be doing twice, once for each relay.

So now you should have (2) wires connected to the other terminal on their 30A fuses, and the other end will be an open ended butt connector, waiting for its next connection.

The next connection will be a combination of two wires from the relay. Grab a short 12 AWG wire, crimp a female fuse connector on one end, and connect it to the #87 spot, leave the other end alone for now.

Next, grab another short piece of 16 AWG wire about the same length as the previous connection you just made. Do the same procedure here, crimp a female fuse connector and connect it to the #86 spot.

Now strip down the ends of the #87 and #86 wires and join them together. You will be forcing this joint connection into the butt connector that you left open from two steps ago.



This is an example to demonstrate the basics. Obviously your wire will be much longer and both fuse connectors will be protected with heat shrink (as well as the relay side). But you can note the black wire is my 16 AWG and the red wire is the 12 AWG. Remember, at this point you will already have a connection from the fan positive lead to the #30 terminal on the relay, which leaves only one spot left to wire up.

The switch!

In this write up I will go over a basic toggle switch, but I would highly recommend a thermostatic switch. Get one that switches a ground so you can simply follow this guide and the guide that comes with the thermo switch and make it all come together.

Toggle switch connection. You will want your switch in the car somewhere that is easily accessible. Once you've secure the location you will need to wire one end of the switch to the chassis somewhere near where your switch is mounted, and the other end of the switch you will have to cut a 16 AWG wire the length from your switch location to the relay location area. Once you cut the appropriate length and have it hooked up to the switch, guide the wire out to the relay area and on the end of the wire crimp on a butt connector.

Now cut (2) 16 AWG wires of equal length (one for each relay) and on one end crimp a female connector and connect each one to the #85 terminal on the relay. You must then join these two wires together and feed them into the open end of the butt connector you secured in the previous step.

Once that is done, put your battery back into the battery tray hook up the positive terminal and the two ring connectors you made for each fan relay. Then hook up the negative terminal and you can now test out your fans by flipping the switch.


All done!

If you have any problems double check to make sure your connections are solid and make sure the 30A fuses are not blown.

You are now done. This is the very basics to setting up your electrical fans properly.

Good luck and have fun.

Last edited by KiLLeR2001 on 02-12-2014, 1:05 AM.

Joined: May 2015
Posts: 3
Drives: 1JZ VVTI S13 Vert

#2 - 05-06-2015, 3:28 PM.

Going to double up here and bringing over my tutorials written for other websites. Here's some additional information:
There's a few ways of doing this but here's the surefire way of having your fans on a switch and a relay.

Parts List:
- '92 to '97 Nissan Altima electric fans (~$30 at junkyard)
- 2 40A automotive relays
- 2 30A fuses
- 1 3A fuse
- 1 automotive switch
- 12 AWG wire
- 18 AWG wire
- Various male, female and ring terminal connections
- Heat shrink
- Solder
- Electric tape

All of those parts would likely cost around $80 total. You can't beat that price! This setup will wire the fans on a low speed only. I've ran my turbo KA just fine on low only with an aluminum radiator. You can chose to use the blue or green wire to to run them on low speed and both the yellow and black wires must be grounded. The relays allow the use of a direct 12V supply to auxiliaries without draining your battery. The switched 12V source turns on the relay when it receives a 12V signal. I would suggest using your cigarette lighter and either splice in or I took the connector off and installed male spade connections accordingly. Keep your fuses within a foot of the battery or 12V switched source, good rule of thumb.

I also had to cut and modify the shroud to fit in my S13. This isn't mine but looks very similar.


Wire accordingly and solder your connections. Enough with the janky butt connectors I see so many novice car enthusiast use because they haven't taken the 10 minutes to Google how to use a solder gun and heatshrink, stop being lazy. And just so we're all clear, Image is the symbol for electrical ground. You can use the negative battery post,a bolt threaded to the body, or your engine block.

For a daily driver I would look into running the fans on a thermoswitch as opposed to a mechanical switch. Also, if you choose to run them on high speed, consider four relays as opposed to two.

1998 Nissan Altima:
Dual speed
low: ~1200 cfm, Amp draw ~16.5A
high: ~1500 cfm, Amp draw ~22.5A

1995 Ford Taurus (3.8L)
Dual speed
low: ~2500 cfm, Amp draw ~23.75A
high: ~3800cfm, Amp draw ~46.5A

Turbo KA Tutorial =>


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Joined: May 2015
Location: Las Vegas, NV
Posts: 5
Drives: '95 240SX

#3 - 05-06-2015, 9:39 PM.

Very nice, i can't keep count of how many people are always asking me how to wire in electric fans.

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