# why is there 4 wires going to fan?



## mattysupra (Oct 31, 2008)

My aircon rad/fan (r34gtr) has 4 wires going to it. 


What are the 4 wires for? I want to override the fan but i dont know which wire i need to send power to. I dont know how to get the fan to turn on to test the wires. 

What are the 4 wires and anyone know which wire does what? 

Thanks.


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## souroull (Jul 21, 2008)

power, ground, sensor reading, fan speed

usually how 4wire pwm fans work... not sure which sensor it's reading

black is ground, yellow is 12v and red is ACC on just about any car i know


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## mattysupra (Oct 31, 2008)

i have a solid Black

Then the rest are black with a different colour stripe on each wire =

1- solid black
2- Black/yellow
3- Black/white
4- Black/green 

This is the colour of the wires coming out of the fan. However, where they get to the plug and plug into the loom the colours of the wires swap around ! 

So you have things like Black/yellow joined to Black/green at the plug! 


Does anyone know how i can activate the Aircon Fan so i can test the wires to see what is 12volt and earth ?


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## AlexH (Aug 17, 2008)

matt, as soon as you switch the A/C on that fan should start spinning, so once switched on you should be able to test what wire does what. although you will need to test it when pluged into the fan, dont test unplugged mate.
also make sure you have a multimeter handy, also a few very thin split pins to probe into the back of the plug.


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## MartinC (Jan 1, 2006)

Terminals 1 and 2 are +12V and terminals 3 and 4 are ground, so to operate at full speed you need to rig up a twin relay to feed both terminals 1 and 2 with +12V. Or if you want to be clever then just ground pin 2 of the relay and you wont need to run extra wires to the motor etc.


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## mattysupra (Oct 31, 2008)

MartinC said:


> Terminals 1 and 2 are +12V and terminals 3 and 4 are ground, so to operate at full speed you need to rig up a twin relay to feed both terminals 1 and 2 with +12V. Or if you want to be clever then just ground pin 2 of the relay and you wont need to run extra wires to the motor etc.


How do i know what terminal is what? Do you have wire colours maybe? 

Where can i find the relay mate? 

I think thats the best idea as i can simply run a switch that grounds it out and the fan will be on at full speed? 


O and ALEX, the fan dont come on at all. I think i have heard it work once over the last 2 years and that was on the hottest day of the year !


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## AlexH (Aug 17, 2008)

thats why i was saying to test the wires leading to the fan, it will let you know if the fan is getting power or not.
besides you dont need A/C it just saps power from the motor, bin it all mate.........


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## mattysupra (Oct 31, 2008)

AlexH said:


> thats why i was saying to test the wires leading to the fan, it will let you know if the fan is getting power or not.
> besides you dont need A/C it just saps power from the motor, bin it all mate.........




LOL, i have enough power! 

O and do you know how nice it is at santa pod etc to have the aircon switched on, looking across at people like yourself sweating your bollox off when its freezing cold in my car? 

I open the windows and you see the cold mist coming out of the window, you then get to see me showing you my finger and laughing at you in your sweaty race suit. 

ANYWAY, Air con stays mate LOL. 


Getting back to it tho, i dont have anything to test mate as no power is being sent to the fan. I think it needs to be super warm outside for it to kick in. All im going to get if i test it is loads of earths i guess untill what ever relay sends 12v to the fan. 

I need to find out how to activate the fan to test mate ? I think !


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## AlexH (Aug 17, 2008)

im pretty sure the A/c dont work like that matt.
once switched on it should start the fan immediatly on low speed, once things get too hot the fan speeds up.
the A/C rad is just a heat exchanger, it removes the heat from the system and the fan opperates to keep it cool at all times.

is your A/C working ok in the car? 
another way to test the fan is to power up the fan on it's own with a power probe or such, but for god sake unplug it first so you dont back feed and systems.

oh and i dont sweat my bollocks off in my racesuit, i keep cool under the mose extreem conditions 
and you wouldent be waving that finger long when your looking at my tail lights going up the strip......................lol


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## mattysupra (Oct 31, 2008)

Alex, i cant test or power up the fan as i have 4 wires. I dont know which wires to send power down! 

I think the fan has a built in temp stat. This is the issue as i dont want to break it. 

Also as someone else has said, "nissans dont run the fan untill they need it" so i cant test here either. 

If someone had a wiring diagram i will work it out in minutes. 


Anyway, seeing your tail lights???? :clap: we will see lol, to be fair mate, i think your setup will beat me on the quarter, think mine is more a track monster. 

Will be fun tho when we get them out together, its about time we finished them and got out there. :thumbsup:


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## MartinC (Jan 1, 2006)

From the diagram the top 2 wires are power, the bottom 2 are ground. As for relay location, there must be a fuse box cover diagram on here somewhere.


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## mattysupra (Oct 31, 2008)

MartinC said:


> From the diagram the top 2 wires are power, the bottom 2 are ground. As for relay location, there must be a fuse box cover diagram on here somewhere.


Hi Martin, 

is there any chance you can post up the diagram your working from mate?


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## MartinC (Jan 1, 2006)

Ok, here it is. You are looking for the Auxillary electric cooling fan motor part of the diagram. Hope it helps you.


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## mattysupra (Oct 31, 2008)

Thanks. 

Is that a online manual your using that i can maybe look at?


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## blue34 (Jul 28, 2005)

Hi Matty, 

Forget the wires to the fan, go in the fusebox in the engine bay. There is a relay for the aircon fan pull it out and look at the underside, it should tell you which is the hi/low current switching side. Then put a short loop of wire across the hi current contacts in the fuse box to test the fan comes on. 

Once you know which wires are which then simply solder another thin power supply cable (or earth cable if the relay is switch is earth driven) to the low current side of the relay if you do this carefully you'll still be able to slot the relay back in to the fuse box and then run the new lead and fit a switch to control the fan. It'll then still operate normally when the switch is off but come on full time when you flick the switch...

Malc


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## mattysupra (Oct 31, 2008)

blue34 said:


> Hi Matty,
> 
> Forget the wires to the fan, go in the fusebox in the engine bay. There is a relay for the aircon fan pull it out and look at the underside, it should tell you which is the hi/low current switching side. Then put a short loop of wire across the hi current contacts in the fuse box to test the fan comes on.
> 
> ...



Thanks ! 

Just the sort of info i was looking for.


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