Thermo fans

Parts needed:
40A relay
on/off switch for in cabin (use something like a 5A or 6A switch for this, not higher)
wire
crimpers
female terminals (blue sheilded type)
solder and soldering iron
inline fuse case and 30A fuse

Intro:
thermo fan setup needs to be run by a relay otherwise it will fry the switch if you try to run that much power through it, so youll need a 40A relay and some decent wiring skills, the way i have wired mine in is theres a thermo switch at the bottom of the radiator, which is normaly used to activate the cluchfan, but yeah, ill refere to this later during pin 86's wiring, now, first things first, on the relay, there should be markings next to each pin, numbering them as...87a, 87, 30, 85,86

Instructions
find a constant positive in the engine bay to link with pin 30, then disconnect battery, this is important when using the wiring as a short can cause alot of damage to components and can do nasty things and give you electrical system ghosts
after disconecting the battery, continue

87a:not used
87: fans (each fan will have two wires going to it, ussualy blue and black, black is gound, blue goes to the relay)
30: pin 30 has two wires, one, joining pins 30 and 85, the other needs to be run to the positive batery terminal (use a 30A inline fuse here between the relay and the battery)
85: refere above, joined to pin 30
86: pin 86 also has two wires, one will run to the thermo switch on the bottom of the radiator, the other wire from the thermo switch will be grounded, which leaves us with the other wire coming from pin 86, this will need to be run into the cabin where you can mount a switch so you can turn the fans on manualy, then from the other side of the switch, goes to ground.

testing
so theres the wiring of it sorted, a few points before your done, are the fans blowing the right way? if its pushing the air to the front of the car, instead of through the radiator, swap the blue and black wires over, should then be corrected.
next, is does the switch you put in the cabin turn the fans on? if no, recheck the wiring. if yes, turn the fans off using the manual switch in the cabin and let the car warm up, once it reaches just over operating temps the fans should still kick in as the thermo switch in the radiator is there (mainly as a back up but can be wired this way if you dont require the manual over ride switch which i recomend for track day cars where temps are pretty extreme and cooling in the pits or between drift laps is required. if you dont want the in cabin switch, then its as simple as using one wire on pin 86 and running it to the thermo switch in the radiator) if it still kicks in on the manual switch and the thermo switch, then your done, hope this helps alot...

if there are questions on this, please PM me and i will get back to you as soon as posible...
please do not attempt this if you are unsure then wait till you have enough info to feel comfortable with what your doing


Taken from nissansilva.com