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Is it possible to control the Thermo Fans?

routier1642

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Ever since my radiator blew up, I've never been happy with the cooling system on my VZ Adventra.

The radiator fans are powerful enough, but I don't like the way the ECU controls them.
Basically, it does *absolutely nothing* with the fans until everything is TOO BLOODY HOT - ****! (like 109 degrees plus) Then turns them on full blast to bring you back from the precipice.
If it's too late, too bad. You'd think Holden would have programmed some better smarts in, like earlier intervention, gradual cooling etc., but apparently not; they prefer a dramatic panic mode. Interesting design decision.

I'd like to be able to determine my engine temperature & have some more control than the ECU's "catastrophic response".

So I have a Davies Craig 0444 Fan Controller & was going to install that to control another fan. A 14" fan that I can use to stop things getting too bloody hot in the first place in stop-start traffic or when parked after an uphill run.
And maybe cut down a little on the heat-soak when I stop. (I could wire it up to run after engine off) If I want my engine to run no higher than 95 C, I should be able to do that.
It's going to be a job squeezing that extra fan in front of the condenser, especially since I now have the trans cooler there, and it does seem a bit silly to have 3 fans on the radiators, especially when it's on the premise that if the new fan does its job, the other 2 fans will never get a look-in. Besides, I've added too many things to this car already.

So my question is:

Is it possible to use a 0444 controller to control the factory fans, leaving the existing control wiring there as well? (cos I don't want to the ECU panicking)
Or will any attempts I make to patch in another layer of control of those fans just upset the ECU & make it throw coders or worse anyway?

Has anyone tried this?

Informed opinions welcome!
 

ozNick

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The fans are also tripped by the AC so tapping into that circuit with the 0444 controller would probably work.

Alternatively get your tuner to change the values in the ECU, but I doubt you let your tuner near your car again.
 

ozNick

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The air-con is also controlled by the PCM so it looks like you're going to need an edit or additional fans.
 

Nut Kracker

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Have a good read of this......
 

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ozNick

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Great stuff Nutcracker

So to test, run a jumper to the low speed fan relay which should turn the fan on. This would emulate the new thermo switch.

This will also set the voltage coming from the PCM to high, and may throw a code. If this is the case, the link from the PCM could have a diode installed to hide the voltage from the new thermo switch but still allowing the PCM to send its signals.

Only issue then could be if the BCM has a sensor for the fan which may or may not concern the BCM.
 

mpower

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If your coolant is in good condition those operating temperatures are perfectly fine - this is not your grandfathers car.
 

Immortality

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Wouldn't it just be easier to have the tune adjusted? any tuner should be able to do this for you.

Engines are run hotter to suit emissions. It's fairly common for modded engines to have a cooler thermostat fitted and have the tune adjusted to suit the cooler thermostat.

As per Nutcracker's post, it would seen that your low speed fan isn't coming on, I would recommend looking into this first as suggested
 
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ozNick

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Wouldn't it just be easier to have the tune adjusted? any tuner should be able to do this for you.

Engines are run hotter to suit emissions. It's fairly common for modded engines to have a cooler thermostat fitted and have the tune adjusted to suit the cooler thermostat.

As per Nutcracker's post, it would seen that your low speed fan isn't coming on, I would recommend looking into this first as suggested

The OP doesn't want to change the thermostat or the other settings, he just wants the thermo fan to kick in at a lower temp.

He could get a tune to make the changes, but from what I understand he has had some bad experiences with tuners and wants to do it without touching the ECU.
 

Immortality

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Well his first stop should still be to figure out why the low speed fan isn't switching on.
 

lowandslow

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The factory fans are by far more efficient than a haphazardly tacked on super-cheap item.

Go and get the temp settings changed in the tune so the fans turn on a few degrees earlier. Fit a cooler thermostat after that if you like.
 
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