I made this diagram for wiring a slim fan a while ago, but I can't remember if I ever posted it or not. With this method, the factory wiring triggers a relay that supplies 12v directly to the fan, and the ECU controls the fan just like it did in stock form. To do this, cut the black and blue wires going to the fan as close to the fan as you can to give you the most room to work with. Then connect them to the relay as indicated in the diagram. The use of the relay allows a constant steady 12v power supply to the fan, similar to rewiring your fuel pump (read the VFAQ for info on what relay to get). As for the fuse, pick the amperage indicated in the documentation that came with whatever fan you are running. If you want to wire two fans to run at the same time, splice the black and blue wires (the ones that went to the stock fan) and run them to another relay in *PARALLEL* (if you run them in series, both fans will shut off in one fails or a fuse blows). This wiring is specific to 1g cars, as I believe the 2g cars have 4 wires going to the fan instead of 2.







Hope this helps!

Thought I'd add to Clint's thread. This is for those who want to run the fans full time, manually:

I'll add to this too.

This is my style of wiring it in a 2G, it will work in a 1G also, just figure it out from the previous diagrams. The 2G stock wiring harness sees IGN +12V at the blue wire for the stock fans and uses a switched ground to turn the fan on and off so you must use the original power and ground to trigger the relay. This method allows for the ecu to control the fans based off of coolant temp like stock, allowing the car to warm up fast and when it gets to temp, kick both fans (instead of just one) on to cool down. Also when you turn on your AC it will kick both fans on, just like stock.

This cabin switch is optional and forces both fans to come on and not shutoff when the ECU calls for it. There's a diagram on the internet somewhere where they use the cabin switch but the drawback to it is if you leave the switch on when you leave the car, that fans will stay on a drain the battery. I added the relay there so when you turn the car off, it turns off the fans too.

Hope I didn't make this too complicated

AAhhh yeessss thank you sam I have been looking for this pic im doing this once my car is up and running since im not using the heat shield I did have both of them but they got thrown away. Don't want to be replacing alt every year.

Sam, I think this would be a better way of wiring it. All I changed was the relay you used for the switch to activate the fans. It is unnecessary. As long as the circuit is being activated by a ground it would not need a relay.

Another bitchin way to control the fans for us Link users is to control them via the FPS, EGR, etc.

I use the FPS solenoid controls for my VTEC and the EGR to map switch.