Thermo fan wiring

YouTube · Post by **El_Freddo** » Wed Oct 22, 2008 11:06 am

G'day eveyone,

I've added as second thermo fan on my three core to keep temps down when I want too. What I want to know is if the factory thermo is earth switched via a relay setup and which wire to tap so that my added thermo fan will switch on with the factory one if I haven't already turned it on?

I've got a double relay setup - both operate the added thermo with the switching wire to: the factory thermo trigger the added thermo to operate, and the other one to a switch in-cab so I can control when its on or in "auto" mode with the factory thermo.

Is it worth wiring in an extra relay for the factory thermo as I've found its rather "lazy" compaired to the added one (which is the aircon thermo from an MY touring wagon) - the aftermarket relay seems to put this fan into a "turbo" mode when compaired to the factory thermo arrangement.

Anyone got a similar setup?

Cheers

Bennie

subybrumby · Post by **subybrumby** » Wed Oct 22, 2008 3:57 pm

I will be keen to watch this thread. I just blew the second fan and nearly cooked the motor coming up the Toowoomba range. The trouble is that it is very difficult to get a replacement fan that will sit in the area provided. (It only has a space of about 5cm.)

I have bought the components to wire the replacement up and will be going for an override switch to have both fans operating when sitting in traffic or whenever the need arises. I bought a blue l.e.d toggle switch from Autobarn for about $7.00 for the job. This will run a wire to a remote relay (Switch) that will ground out both fans when required. (Blue for cooling) That's the plan anyway. Its an EA82T Brumby, Very litttle room, going for the 12" Craig Davies. As I recall, both my brumbies have the second fan coming on with the aircon at the moment and the first fan thermo switched. That's what I think they have been doing anyway.

Matt · Post by **Matt** » Sat Oct 25, 2008 1:08 pm

Original both come on with the air con, but a relay and you can fix that. (they do this to try and keep the aircon cold when you are sitting at the lights, by passing air past the condenesor) but really you can have them both wired up to come on when the engine heats up. I have 2 big factory fans both on a relay, triggered off the factory loom, mounted in my ute and have had great sucess and also a manual overide.... you know when they kick in but, the idle drops about 50rpm.... Just don't run them the hole time as it will heat the engine up at highway speed, because the air is actually slowed down past the radiator

YouTube · Post by **El_Freddo** » Sun Oct 26, 2008 10:21 am

Cheers Matt, I'm still after someone with specific knowledge of the wire to tap in the factory thermo loom to trigger the added thermo fan...

Matt wrote:Just don't run them the hole time as it will heat the engine up at highway speed, because the air is actually slowed down past the radiator

Interesting - are your thermo's powered by the standard wiring loom? If my car's getting hot on the freeway flicking the added thermo on before the factory thermo kicks in brings the temp down even at 110km/h on the freeway... Mind you I have 3 spotties "blocking" the grill area of the radiator, not that it would get much air through there anyway...

Cheers

Bennie

SuBaRiNo · Post by **SuBaRiNo** » Sun Oct 26, 2008 10:42 am

I have read your post twice and im still confused at what your trying to do. Hatchie (ej22 in MY body) is set up like this.... factory MY radiator set up and wired as per standard. Trigger wire for this is the single wire sensor on the drivers side of the radiator. This turns on when the radiator gets too hot.

My 2nd fan is aftermarket and i have wired that through my own relay using the factory temp sensor on the EJ22 motor as the sensor... turns on only when the motor is at operating temp.

Both have been wired to switches to turn them off in an event of a river crossing but apart from that they automatically function.

Dave

YouTube · Post by **El_Freddo** » Sun Oct 26, 2008 11:27 am

SuBaRiNo wrote:I have read your post twice and im still confused at what your trying to do.

No worries dave. This is what I have:

- Standard factory thermo
- Added electric thermo in place of the mechanical engine fan that no longer fits

What I'm trying to do is have the added thermo switch on when I want it to or when the factory thermo kicks in - so that in these situations I have both thermos running without me doing anything.

I have two relays setup to run the added thermo - One is triggered by an in-cab switch. The other relay is to be switched by the factory thermo wiring - I just need to find the wire to reference the voltage when the fan is running to trigger the relay.

I'm also wondering if the L's thermo wiring is Negatively switched which would mean that I need to change the relay's wiring for it to work properly...

Hope this helps out, if not I'll draw a diagram and post that up.

Cheers

Bennie

SuBaRiNo · Post by **SuBaRiNo** » Sun Oct 26, 2008 11:53 am

hmmm ok... i know this... L's have a 2 wire system for the thermo fan trigger which is also on the radiator (i belive on the drivers side). How it is triggered im not sure... by bridging across the 2 wires on this sensor the fan will come on though. To test if it is negative or positive triggered try this....

With a old school (globe type) test light.... put the clamp on the neg side of the battery and probe the fan sensor terminals with the probe. (make sure IGN is on). If it is negative triggered your fan should turn on when you probe one of these wires. The same can be done by testing if it is positive triggered by putting the test light clamp on the positive on the battery and re-probing the wires again.

This would help you find out how it is triggered and which wire would need to be triggered to get the fan to run on command.

Based on this you can work out if you need multiple relays and if some diodes would be needed.

It's likely to be negative triggered... a closer look at some wiring diagrams would probably make it more clear.

Dave

YouTube · Post by **El_Freddo** » Sun Oct 26, 2008 12:00 pm

Thanks Dave, I'll probabily give it a go later in the week once the last assignment is in (YAY!) and I'm done with uni for the year...

Cheers

Bennie

Post by **Captain Obvious** » Sun Oct 26, 2008 5:33 pm

freddo the l's are triggered by a thermo switch on the radiator driver side from memory and im pretty sure it switches the earth! i had 2 thermos on my RX with 3 way switch middle was off, (off was for water crossings) one was on all the time and the other was thermo by the temp switch on the rad, was a little messy but its worked, they also were independent of the factory wiring, that means running them straight of the battery, they get heaps more power but make sure you run good size wire to them as they draw heaps of current!!!

also i had both come on at once didnt have to worry then as i would know it would always stay cool.
now the ej20t computer worries about all that in the lib:)

bryan

YouTube · Post by **El_Freddo** » Wed Oct 29, 2008 12:31 pm

Captain Obvious wrote:freddo the l's are triggered by a thermo switch on the radiator driver side from memory and im pretty sure it switches the earth! i had 2 thermos on my RX with 3 way switch middle was off, (off was for water crossings) one was on all the time and the other was thermo by the temp switch on the rad, was a little messy but its worked, they also were independent of the factory wiring, that means running them straight of the battery, they get heaps more power but make sure you run good size wire to them as they draw heaps of current!!!

Hey Bryan, I'm thinking this setup may be a better way of doing it. My thoughts are to not interfere with the factory thermo wiring, rather use the two wires to run the thermo fan as the power and the switch wires on a relay for each fan.

In theory the factory thermo fan wiring will be telling two relays to turn on (in place of the standard thermo fan) the two thermo fans. From this I can run a secondary set of relays that can be operated by in-cab switches, basically the same as your setup.

Clear as mud? I'll have to drop into jaycar and get me some supplies when I can...

Cheers

Bennie