Modding the cooling system wiring...

[97spyder maayng]

So i just installed some nice 12" FAL slim fans, to make room. I hooked up the wires for both single fans properly, but my AC fan won't come on, no biggie. I'm planning on removing the wholeAC unit (i have a spyder, so when its hot i drop the top ) Should i wire the second fan in parallel or series?

Parallel: both fans take equally 100% of volts, so super-uber cooling all around the rad, instead of it being uneven. Is this overkill? OR
Series: both fans get equal amount of volts, but it is 50% of the fans potential. Same as 1 fan running on high 24/7, except instead of cooling 1 side of the rad, it cools the "entire" rad (over 70% recommended by FAL)

I'm thinking of running it as parallel, considering that a colder rad is a better rad (torque/fuel economy), but is this always the case?

 

[eclipsegsx1736]

I just finished wiring my stock fans following a VFAQ instruction. Its very easy, and here's what it does after the mod:

1. Whenever the ECU decides your cooling fan should come on, the A/C fan comes on as well, to help cool the radiator better. (Basically the mod makes it so whenever one fan is on, the other comes on too)
2. It allows you, using a simple toggle switch inside the cockpit, to override the ECU's control over the fans, so you can turn both fans on with the flip of a switch. So, you can leave the fans on even when the car is off, say to cool the engine faster if you need it to be cold to work on it, or to prevent overheating after shutting the engine off.
3. If you don't override the ECU's signal and leave the switch OFF, the fans will still come on when the ECU decides they should come on. So you dont have to worry about remembering to turn on your fans in case you forget.
4. The only disadvantage is that you could theoretically forget and leave the fans running with the switch ON after the engine is off, and run your battery down. But the fans are kinda noisy, you wont forget.


I did this mod yesterday, and its awesome. It was simple and its great to have control over the fans, and now I can actually use the A/C fan for something, because I NEVER use the A/C while driving, so normally the fan never gets used. I see no disadvantage, just be sure to wire it neatly, so the wire that has to travel thru your engine bay doesnt get tangled in the throttle linkage or something.

http://www.vfaq.com/mods/wayback/2gcoolingfan.html

 

[97spyder maayng]

thanx for the reply, I remember reading this before, but considering i have a turbo timer, i don't need a toggle switch to turn on the extra fan after a long drive.

But after reading this in closer detail, i see it's also running in parrallel, so i guess that's what ill do.

thanx again

 

[luv2rallye]

Whatever you do don't connect them in series. That will not run them at 50% and most likely will burn them out. You could connect them in parallel if your relay and wiring can take the extra current without melting. But why not connect them to the same stock connector wires? The ECU controls when each fan turns on automatically based on temperature sensors. Yes it does force the condensor fan on when the A/C is on but it will also turn this fan on even without the A/C on if the temp gets high enough. Plus all the correct wiring and relays are already there. And it will rob less power if it only needs 1 fan on.

 

[sweet97]

I did not check the vfaq yet so cut me some slack please. I am about to add a second fan, in fact it is on the radiator now. If I just tap into the first fan's wiring will that cut the amps/volts in half to each or will both see 100% power? mark

 

[luv2rallye]

If I just tap into the first fan's wiring will that cut the amps/volts in half to each or will both see 100% power? mark

Assuming the first fan's relay and wiring is large enough to handle the extra current, you should see 100% power on both. Usually the relays are big enough. The wiring probably is although I would make sure the common supply wire before it splits to go to both fans does not get warm since you will now be running twice the current thru it.

 

[sweet97]

Thanks! Mark

 

[steve]

Like a lot of things you find online you need to think about what's being presented rather than just following it. The VFAQ referenced runs all the current for the fan through the switch. That's not a real good idea considering that by connecting to the ground side of the relay coil (the same side as the ECU) you can get the same control over the fan by just switching the control current to ground. That just parallels the ECU fan control with the switch.

Another advantage is you don't have to run any wires out to the fans.

Steve