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Thermo Fan Wiring


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#76 Tiny

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Posted 01 December 2013 - 08:25 PM

Matt,
Are you going to want override switch or anything inside the cabin? (To turn them on manually if you wanted to?)

I can help with this, remind me tomorrow pleas!

#77 _LH SLR 3300_

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Posted 01 December 2013 - 08:35 PM

Do you think I should fit a manual override switch? I would really appreciate your help as I've spent the better part of the afternoon trying to get my head around this. Thanks



#78 SmacT

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Posted 01 January 2014 - 11:06 AM

How did you guys go with this? I will be wiring mine up soon and have seen so many variations I too am confused. Easily done, mind you.

#79 axistr

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Posted 05 March 2014 - 07:31 AM

Sam use the output fan control wire from your computer to control a relay/s to bring in both fans. (computer switches earth when cut in occurs)  I would also use a manual override switch in the circuit.

 

I use a override rocker switch which has a light in it when on. When the fans are in automatic selection the light still comes on so I know when they are cutting in and out, mine are hard to hear when they are on when driving, and also illuminates when manual mode selected. Fool proof.   



#80 SmacT

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Posted 07 March 2014 - 08:46 PM

Once again Lenny, thankyou! I haven't done much lately, new job taking up my time, but getting back into it now. I like the light idea. Brilliant.

#81 SmacT

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Posted 08 May 2014 - 10:23 PM

Finally wiring these Aus up, but want to make sure I have this sussed. I am having my memcal set up to run the fans from the ecu (car runs a HSV 304i/T5/ commodore radiator/ thermo fans). Which is from terminal c1 I believe.

The memcal will have a vr tune, which apparently has the option for a two speed fan. I don't think the Aus I have can do that, however, as they have no white wire, just black and red. Any one know?

Other option I thought was to run a wire from c1 for one fan, and a second wire from the a/c fan control terminal for the other, and have the memcal set up to trigger them staggered - the first on at 92 degrees, the other chiming in at 98 or so, with both shutting off at 87. Anyone know if this will work?

Once I have that sorted, then it would be trigger wire/s to relays, along with fused power wires from the alternator b+ (standard commodore v8 alternator) to the relays, then earth the fans and relays. Does this sound right? Any opinions welcome.

#82 axistr

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Posted 21 June 2014 - 05:39 PM

Sam I wired up my fans last week. I use the HI & Low fans relays and cut both fans in together. I got my ECU memcal to trigger at 92deg rather than the 100deg factory setting.

 

On my SLR the ECU will trigger a third relay because the ECU fan output switches from power to earth(earth is cut in). I use a third relay because the way I have wired it up allows me to also have a manual override switch.

 

Both fans have their own 30amp power fused circuit and relay. and both fans will also come on every time the air conditioner compressor clutch cuts in through the A/C relay. The third relay is wired up so the relay 30 & 87 terminals are a through earth circuit to trigger the earth side of the 85 terminals on the fan relays . The third relays 85 terminal has 12v power supply and the 86 relay terminals will go to the ECM trigger wire, from memory its blue/white. When the computer is not controlling the fans it has a 12v power supply to the 86 terminal. when the ECM cuts in the computer switches to earth and the third relay cuts in and in turn triggers the fan relays.

 

The manual over ride circuit switch earths out the 30 terminal on the third relay to over ride the auto trigger on this relay. I run two wires back to the manual over ride switch which has a light in it. An earth wire and the second wire is wired to the fans relay output so every time the fans cuts in I can see that they are operating from the light in the switch. The fan power output goes to the switch light and an earth on the other side of the light. Just use the switch to switch earth and a second short wire back to the earth side of the light.

 

I have wired up the hatch this way and works great. When both fan cut in they are only on for around 30 second rather than trying to stage both fans,  in the long run staged fans will probably stay on for twice the time anyway.

 

Hope this helps.         



#83 SmacT

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Posted 24 June 2014 - 09:11 PM

Thanks, it does. I have dummied up the wiring and taken it to the local auto sparky for a second op before I wire it up. Thanks again.

#84 _glennhailstone_

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Posted 28 August 2014 - 09:10 AM

Wow, super confusing thread.

 

Most thermo fans come with a simple wiring diagram. Note: this is for simple fans.

 

Constant hot power from battery.

 

Temp sender wire

 

IGN wire

 

Power to fan

 

Earth fan

 

My only question is, where is the best place to take the ignition power from. I was thinking the fuse box. Heater fan or radio. Just something so that the power only comes on when the ignition is on.

 

Thanks,



#85 TerrA LX

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Posted 28 August 2014 - 09:38 AM

My only question is, where is the best place to take the ignition power from. I was thinking the fuse box. Heater fan or radio. Just something so that the power only comes on when the ignition is on.

 

Thanks,

 

Anywhere where that powers up when the ignition is switched on.
I would not take it from a high current (amp) feed.

The ignition wire is used to sense when the car is on or off, not to power the fan.



#86 _glennhailstone_

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Posted 28 August 2014 - 10:23 AM

Thanks GM



#87 Marks LXTorana

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Posted 09 July 2017 - 08:57 PM

Hi guys, I'm reviving an old thread rather than start a new one as most of the info is here. I finished wiring my thermo fans today pretty much as recommended here, using 2 relays and main power from alternator. My only question is the validity of the over-ride switch, which I didnt do. Thinking about it logically, the engine should maintain a constant operating temperature (within reason) by opening/closing the thermostat and then kicking in the fans if the car is not moving to get air flowing through the raditaor. So logic keeps telling me if the thermostat and fans are doing their job as planned, an over-ride is not going to add any value unless by chance the circuit has failed somewhere, in which case the over-ride probably wont work anyway.

 

Wouldn't an over-ride simply be over-working the fan when not required? Am I missing something?



#88 Bigfella237

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Posted 09 July 2017 - 09:56 PM

I think it comes down to the "hysteresis" of the temp switch, they will usually turn on at say 95° and off at say 88° (or whatever temps the switch is set at) to stop the fan constantly cycling on & off once the trigger temp is reached.

 

However if you switch the fans on manually they will, in theory, run at 88° all the time, which gives you some breathing room if you were towing on a hot day, or crawling through city traffic, or whatever.



#89 axistr

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Posted 10 July 2017 - 04:54 PM

Mark, I haven't needed to use my override fan switch on either car. The idea was to bring in the fans manually in case I ever had an auto triggering problem. The other reason was as stated above give me some breathing room in the event the car was having cooling issues on a hot day in traffic with the AC on, My theory was I could bring them in a bit sooner and help stabilise the cooling system temp, as soon as the thermostat opened the coolant flow would be cooled rather than wait till it got over 90 degrees before auto triggering. 90c is close to boiling point so there isn't much lee way if everything isn't up to scratch. The factory delco engine computer fan cut in setting in the SLR was 98 degrees on low and 100 on high. When I got it re programed to suit my Torana  I got them to set the cut in at 92 with a 82 thermostat. The factory stuff doesn't allow for much lee way.

 

I was probably being a bit paranoid but I still like to some control over automation.      



#90 cameron

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Posted 11 July 2017 - 02:59 AM

I prefer to use the kiss principle and run the Derale's PWM Fan Controllers. Soft start with PWM on demand fan speed control (0-100%), fans up to 65 amps, automatic circuit breaker, override circuit built-in.

 

Nice and simple and soft quiet start-up with its modulated control. No more noisy flat out or off.

Been using PWM for years and run everything with it from fans to fuel pumps.

 

 

16796-with-bullets.jpg

16796-alt-image2.jpg

 

 

Cameron


Edited by cameron, 11 July 2017 - 03:00 AM.


#91 Marks LXTorana

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Posted 11 July 2017 - 07:26 PM

Thanks for the replies guys, food for thought but I'll see how the temp goes without it for the time being. I like the idea of the PWM fan controllers too..



#92 Tiny

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Posted 11 July 2017 - 08:07 PM

I ended up ditching my home made unit because I thought it wasn't good enough!
I bought a SPAL PWM-V3 controller and it has been AMAZING!
It uncovered a dying motor (which is what killed my home made controller!! - not happy :(

Anyway, I haven't looked back since fitting the PWM, it's been awesome. I'd definitely investigate the unit shown above!!




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