Manually controlling electrical fans

[DiscoDino]

Hi everyone...

We are in the midst of finishing our truggy and with a rear radiator and dual fans, we'd want to have control of the fans for various reasons...of course, we know the engine's computer will ensure they run as needed...but some manual control when needed isn't bad...

In specific, we want to be able to "force them on" when we are slow crawling, going uphill for a long time (dual sport) with the cab enclosed (vs. no cab/windscreen)...and we want to be able to "force them off" when we are doing water crossings, etc...

The questions I have:

1. does anyone know of a switch from Carlingtech that can fit the normal Contura housing that I can cut OFF the fans AND have it light up (of course to keep me and co-pilot aware)...on the "ON" side it is easier...

2. also, has anyone used their new rotary version of the switch? I'm thinking they must ONE switch that is in the middle for the engine to do it's thing...can turn one way to cut off (and light up red let's say), and then also turn right to force them on all the time (and light up green let's say)...any idea?

3. and finally, what would be the "electrical wording" of such switches: a) the one that lights up when you cut something OFF, and b) a switch that lights up in the two positions it has (other than neutral), where one position is cutting something OFF while the other lights on easier while turning something ON.

4. finally, I assume it'll be best for us to put diodes from the engine harness to these switches en-route to the fans...so that there is not "reverse trickle" of the current for any issues...is that your opinion as well? What size diodes would you recommend (or for us to assess what size is best?).

5. Anyone you know I can contact directly? This **** is WAAAY over my head

Thanks!
Nadim

 

[patooyee]

What ECM are you using?

I think most of the GM ECM's have an option to turn one fan on when the a/c comes on via a signal from the refrigerant pressure sensor. Assuming you're not using that pin, you could just run that pin with a toggle switch which would override the temp settings and turn the fan on.

 

[DiscoDino]

Thanks! That's a great idea!

 

[MihlfeldL2005]

Re:

That's how most of the aftermarket controllers work for the Taurus fan conversion on a TJ. You wire them in to the ac system so that it kicks on low when you turn on the ac. I chose to run mine to a switch on the dash though for manual control. The only issue lies that it will still
kick on if the temperature rises, it'll kick on low even if you're in a river crossing scenario. You'll want to also run a switch on the power that goes to the fan

Sent from my SM-G900T using Tapatalk

 

[gottagofast]

Labels would be on off auto...

You would use a standard on off on switch... The fan wired to the center and the ends wired to the computer and to 12v pos

I'd say any of the companies that make custom labeled switches could hook you up

 

[tiny]

How about an on- on- on switch. With one of the on's lighting up is off light.

 

[Toddy]

Doesn't the GM computer break ground to turn can on and off? May be wrong but thought that's how they do it.

 

[patooyee]

Doesn't the GM computer break ground to turn can on and off? May be wrong but thought that's how they do it.

Yes.

 

[RustyC]

A double pole double throw would work if I'm thinking correctly. Rocker style switch have 3 positions, up, middle and down.
Up position will be FAN ON and will connect the ground of the fan relay coil to ground. Turning on the relay / fan.
Middle position will connect the ground for the relay to the ECM as normal allowing the ECM CONTROL of the fan as needed.
Down position would leave the ground for the relay open. Keeping the FAN OFF

This is with the relay having battery power supplied to relay terminal 30 and 85.
Pin 87 to the fan.
Pin 86 to the above switch.

I would use a big ass blinking light on the fan off side. Having an off position for a fan is asking for an overheated engine. I have personal expiriant with this, trust me.

 

[John Galbreath Jr.]

Having an off position for a fan is asking for an overheated engine. I have personal expiriant with this, trust me.

This! I have seen WAY more overheated engines from off fans, than those that needed help in a deep water crossing.

 

[patooyee]

This! I have seen WAY more overheated engines from off fans, than those that needed help in a deep water crossing.

x3

If you don't do water crossings, I wouldn't worry about an off position. Maybe hook up a buzzer to it if you HAVE to have it. Google "12-volt piezo buzzer."

 

[TBItoy]

Re:

Who crosses water that deep anymore?

 

[RustyC]

The op used the term windscreen and not windshield. I'm thinking he's across the pond somewhere. Maybe even trying to get here, not that I blame him.

 

[gottagofast]

I agree w the overheating comments....

I've personally never seen a fan running in the water hurt anything not that it can't

I've never had any desire to turn my fan off

 

[patooyee]

I agree w the overheating comments....

I've personally never seen a fan running in the water hurt anything not that it can't

I've never had any desire to turn my fan off

I have seen mechanical fans bend blades and destroy the radiators when they hit the water. And I have seen electric fans self destruct when the blades hit the water. I've also seen them go through water without any issues.

 

[DiscoDino]

Hi everyone and thanks for your input - very valuable and we loved it by repurposing two ARB switches with some internal switch modifications (my buddy/electrician did the detailed work so I can't take credit for it...).

The reason we want to shut them off is for water crossings: we are building the truck to compete in the Croatia Trophy, Rally Breslau, some U4 in Europe, and other races...all the parts were sourced from the US...but we went with a Land Rover Defender 110 pick up as a base.

Radiator and fans are up high out back above the 32G JazSpeed fuel cell, but again, anticipating the worst in race conditions...

Once I have a more detailed solution I'll post back up for others' future needs...

Thanks again...

 

[ToyotaTom]

You got a build thread for your buggy? I have always liked the European style winch challenge races. Being able to shut off your fans in that type of environment will be key. I have personally blown up a fan on a Ground Mobility Vehicle during a water crossing and they said it couldn't be done lol.