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JohnRambo

Wiring twin fans

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Merry xmas all

 

i have a single 14" fan that runs off a 25a fuse and struggles with Auckland traffic.

 

i want to switch to 2x12 and was thinking of a hi and low temp setup.  However I want to avoid running another fuse and relay and using up 2 outputs.

i would also like to wire up and auto/override witch for track days.

 

any thoughts would be much appreciated

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You could run one of the fans from a temp switch in the radiator, and then the other triggered by the ECU.

Does your radiator have a fitting for a temp switch already?

You can buy different ones which come on at different temps, depending on what thread pitch etc it is.

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Thanks. Prior to the link I had a fan controller which had a temp sensor in the top radiator hose which I could put back into service.

does any have a recommended temp to have the second fan turn on?

i have a skyline and might look to see if I can remove the fpcm on aux 3 which would give me a spare output to drive the second fan

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Hi JohnRambo,

I would set the radiator top hose capillary tube thermatic fan switch to activate at 90 deg c.

I would set the second fan to be activated via the relay from the ECU AUX O/P and also have it activate with the A/CON on so you have an A/CON  condensor fan.

Have you no spare AUX outputs including any spare injector or ignition outputs to drive the fans.

Regards

Dave.

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Thanks, I set the old fan controller to 90deg and the link to control the other fan at 96deg

I don't have a/c in my car and I used the original a/c aux for a shift light.

I noticed on my link one of the aux was for a CE light which is only for map and ECT, could I use this aux for the second fan.  I have a good water temp gauge.

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The CE output on the Link ECU will activate for any fault noticed by the ECU. It would be possible to use this output for controlling a second fan, but you would then not know if a fault had been noticed by the ECU.

Which ECU do you have?

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I have a g4 gtslink.

the current output is only for map and ect.

i'm in the middle of setting it up so I can run a win tablet as the dash for the track, or maybe leave it permanently for the street, which would always have pclink running to show me any errors.  I also rely on the engine limiting functions to protect it.

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I'm getting rid of a clutch fan on another Skyline and putting in 2x12' fans as well.  This car has the a/c however, could I remove the stock condenser fan and just run the 2x12? would that be enough for the a/c?

I think this is what DavidK was getting at.  Just want to confirm it

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Hi John,

This should work fine so long as you the ECU is switching on the A/C compressor clutch. I would set one of the fans to 'AirCon Fan', and then the other fan as a GP output that activates when the first fan activates. This way they will both come on when the ECT is high enough, and both come on when the A/C compressor clutch comes on.

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Ok, I had one fan as the aircon fan and the other as engine fan.

So I need to change my engine fan to GP output with something like this

 

virtual aux value1 = on

set it to engine fan

 

aux value1 = on

set it to aux inj 8 (which is the aircon fan)

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I would set the fans up like this:

 

Fans.PNG

When ECT is 96 C or higher OR AirCon Clutch is on, Aux 1 will turn on. When Aux 1 turns on, Aux 2 will turn on also. I'm unsure which Aux channels you are using, but you get the idea.

Edited by Scott

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I would try it without and see if there is a problem. If there is then you could use one the ECU's timers to make this happen. You would make the timer activate when the 'AirCon Fan' aux channel turns on.

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I've tried this tonight and something fully strange is going on.

It is a GTSLink and I set Aux 2 to be the aircon fan.  I ran the test and it was ok.  However, when I turned the car off it must switch to ground and the fan started to run when the car is off.

It doesn't do this on Aux Inj 8 though,  I tested with Aux 2 and Aux 1.

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You need to make sure the power to the fan is removed when the key is turned off.

What you are seeing is a typical back feed. The ECU has no control over the drive once it is turned off the internal circuitry has a path to ground which will then allow the fan to run.

If you hed to

Navigation:  G4+ ECU Tuning Functions > Auxiliary Outputs >

Wiring Auxiliary Outputs

 

In the help file it gives a much longer explanation.

 

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Fresh cup of coffee and the light bulb turned on, my fans are run directly from the battery like the fuel pump so it has a constant 12v.

If I put the fans on ign 12v it will sort it.

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The ignition switched relay will work well. You mean a label of the Aux Outputs in PCLink? 'Engine and A/C Fan 1' and 'Engine and A/C Fan 2' would fit in the space allowed.

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You are going to need to control the fans via relays regardless, and you should be able to find an ignition switched +12v pretty easy, so I would go that way if I was you.

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I would use two relays. On each relay:

Pin 87 would go out to the fan (supplying +12V)

Pin 30 would go to a battery power supply (fused).

Pin 86 would go to an ignition switched power supply (fused)

Pin 85 would go to the ECU's Aux Output channel.

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