MY thermo wiring trip switch for one fan only

YouTube · Post by **El_Freddo** » Sat Jan 07, 2012 9:14 pm

G'day all,

I'm after any info as to how I should go about modifying the wiring on Sunnie the Brumby so that one thermo fan comes on all the time when I flick an in-cab switch without triggering the second thermo fan. Both are triggered by the radiator switch at present.

The idea is to have an "ON/ON" switch - on to trigger one fan only when ever the ignition or accessories is on and the other on selection to return the fan to operation by the AC system or the radiator temp sensor. So on all the time will be used in the hotter months and the on via radiator sensor/AC will be for the winter months.

The reason for this is that Sunnie the Brumby is suffering cooling issues in the hot weather we've been having and the slow traffic - but when you have the AC on he's happily got his temp gauge sitting in the normal operating temp spot, nice and cool. When he's hot the gauge goes up to half until the thermo's are triggered. If I can have one on all the time in summer I reckon he'll be sorted.

Cheers

Bennie

NachaLuva · Post by **NachaLuva** » Sun Jan 08, 2012 12:23 am

Can you change the sensor so it comes on earlier?

revmax · Post by **revmax** » Sun Jan 08, 2012 6:06 am

you could wire it up the same way you do driving lights.
A switch to activate a relay, the relay then feeds the power to the fan.
Just tap into the same power wire that supplys power to the realy for the first fan at the relay

YouTube · Post by **El_Freddo** » Sun Jan 08, 2012 1:31 pm

revmax wrote:you could wire it up the same way you do driving lights.
A switch to activate a relay, the relay then feeds the power to the fan.
Just tap into the same power wire that supplys power to the realy for the first fan at the relay

Having someone explain this to me makes more sense than it did before in my head...

Thanks Revmax, I'll have to knock up a wiring diagram to post to show on here, this way others might see a mistake I've overlooked

Cheers

Bennie

YouTube · Post by **El_Freddo** » Sun Jan 08, 2012 10:03 pm

Wiring diagram:

Anyone see an issue with this working? I'm keen to hear about it/them

Cheers

Bennie

GOD · Post by **GOD** » Sun Jan 08, 2012 10:16 pm

So in that diagram you've disconnected the primary thermo fan from its original wiring and plugged it into a new relay instead, right? And the second fan is still switched by the temp switch or air con switch as standard? Sounds good to me.

Dane.

*edit - assuming MY fans are earth switched

YouTube · Post by **El_Freddo** » Sun Jan 08, 2012 10:26 pm

GOD wrote:So in that diagram you've disconnected the primary thermo fan from its original wiring and plugged it into a new relay instead, right? And the second fan is still switched by the temp switch or air con switch as standard? Sounds good to me.

Dane.

*edit - assuming MY fans are earth switched

Yes and Yes to the edit

Sounds good to me too

Cheers

Bennie

SuBaRiNo · Post by **SuBaRiNo** » Sun Jan 08, 2012 10:36 pm

Looks good.

Could also be done with a nomal on/off switch and a change over relay if u want to get fancy.

Dave

YouTube · Post by **El_Freddo** » Sun Jan 08, 2012 10:50 pm

SuBaRiNo wrote:Looks good.

Well that's it, I've got the official seal of approval

Thanks Dave, I know you're a busy fella these days!

SuBaRiNo wrote:Could also be done with a nomal on/off switch and a change over relay if u want to get fancy.

Problem with this is that I only want one fan to come on, not both. It would be easy to trip the system to have both fans on like the AC was working, but it's not what I want to do, I still want that second thermo to be triggered if the temperature was to rise enough to trigger it. I'm convinced that it won't come to that, we've not had cooling issues with this brumby before. But that's not to say that it could have a new water pump or a leaking head gasket, there's no indication of a leaking head gasket (which is totally awesome too).

Going for a basic, easy and cheap modification to look after this first, then go from there if other things arise...

Cheers

Bennie

SuBaRiNo · Post by **SuBaRiNo** » Sun Jan 08, 2012 10:53 pm

No no.. My way would work how u want. But if u knew how then u wouldn't have started this thread.

Dave

YouTube · Post by **El_Freddo** » Sun Jan 08, 2012 11:11 pm

SuBaRiNo wrote:No no.. My way would work how u want. But if u knew how then u wouldn't have started this thread.

Yeah, I should have already known this, you're an electrical wiring/systems guru! But I'm sure you already know this, even if you won't admit it.

Cheers

Bennie

phantomD · Post by **phantomD** » Tue Jan 10, 2012 10:45 pm

Just run both the fans all the time?? That's what I'm doing!

revmax · Post by **revmax** » Wed Jan 11, 2012 5:10 am

Both fans all the time and the engine is not at optumum temp and will use more fuel.

steptoe · Post by **steptoe** » Wed Jan 11, 2012 8:15 am

think the "change over relay" is the 87, 87a relay (twice the price of a normal relay) , so when you switch relay on with manual switch inside it will operate fan by say 87, then when you switch off , 87a should be connected back to the "auto on" side of the wiring

YouTube · Post by **El_Freddo** » Wed Jan 11, 2012 12:39 pm

steptoe wrote:think the "change over relay" is the 87, 87a relay (twice the price of a normal relay) , so when you switch relay on with manual switch inside it will operate fan by say 87, then when you switch off , 87a should be connected back to the "auto on" side of the wiring

Ah yeah makes sense and would be very easy to do. I'm still going to go with the wiring diagram above as I'm using parts I've already got from the shed.

Now for this victorian weather to settle down so I can get out there with some comfort! It's expected to snow on the alps today and it's VERY windy and very bloody cold too!

Hopefully Australia day is a pot load hotter and a lot less windy than it is today.

Cheers

Bennie

steptoe · Post by **steptoe** » Wed Jan 11, 2012 4:37 pm

Not just Victorian weather, the east coast up a little further has it too, and by the sounds of things TC TOONGA is about to hit Karratha !

Silverbullet · Post by **Silverbullet** » Wed Jan 11, 2012 5:11 pm

Are you talking about un-seasonally cool weather? because it's about 22-23C all week here with showers, unheard of!

Not that I'm complaining

MTB92 · Post by **MTB92** » Wed Jan 11, 2012 8:24 pm

El_Freddo wrote: Now for this victorian weather to settle down so I can get out there with some comfort! It's expected to snow on the alps today and it's VERY windy and very bloody cold too!

Thats not what i want to hear!

I am racing a MTB National round at Mount Buller next weekend. might be a bit of a contrast from here, where at almost 6.30 its still 32 deg.
Actually, i think it might have been a bit cooler than usual here aswell lately.

YouTube · Post by **El_Freddo** » Thu Jan 12, 2012 12:04 am

MTB92 wrote:Thats not what i want to hear! I am racing a MTB National round at Mount Buller next weekend. might be a bit of a contrast from here, where at almost 6.30 its still 32 deg.
Actually, i think it might have been a bit cooler than usual here aswell lately.

Mt Buller 7 day forcast. Looks like some good weather up there for the weekend except for the rain on the sunday. Mid teens at that altitude =

But still pack your long johns

And it's Victoria too, you never know, we could get a freak heat wave in the next 12 hours! Thus why I need to sort out this temp issue!

Cheers

Bennie

phantomD · Post by **phantomD** » Thu Jan 12, 2012 10:37 am

revmax wrote:Both fans all the time and the engine is not at optumum temp and will use more fuel.

Well I respect your opinion, but with the mechanical fan the car temperature used to fluctuate all over the place and it would generally run at 1/4 on the gauge. With both electrics running all the time it is JUST below half way and never moves (unless we have a stinker of a hot day like yesterday!).