1UZ Celsior Hydro fan always going fast

[TurboRA28]

Hi all, I recently wired up a 1uz from a Celsior with the hydro fan ecu.
It always seems to spin fast though, even when the engine is cold. If I unplug the fan ecu it actually slows the fan down. Should it spin when the engine is cold?

I could only find one diagram for the fan ecu and not sure what engine it was from. I think I got everything correct but maybe not.

Any ideas? Pin outs? etc

Thanks
Joel

[Sciflyer]

the default mode for the fan if something in the aircon system or cooling system is not right is to run flatout

Is your aircon functioning correctly? Things like pressure switches in the aircon pipes are all connected to the fan ECU or maybe a temp sensor is not connected somewhere

THe good thing is it is possible to have fan speed governed automatically as per usual but also have a manual fan switch wired in, this is what i have done and it all works with the aircon system removed

[TurboRA28]

AHh ok I don't have any aircon connected.
So think there might be some air con wires i need to earth or give power or something?

[Gabe]

Joel,
If you open the fan ECU, the pins on the circuit board are labelled with what they do.
Do you have the temp sensor connected? The Hydro fan has it's own sensor in the radiator.

I have a wiring diagram somewhere if you're still stuck.

[TurboRA28]

Cool ok so I can get the pin outs easy enough.
I do have the original temp sensor in the radiator and connected.
I have the tacho connected also.

[CrUZida]

As above.
Its like the Toyota Climate Control. All the sensors have to be wired in and reading correctly for it to work.

The fail safe setting is full speed.

It still spins quite fast when the engine is cold (visibly fast that is) but doesn't make a lot of noise

[TurboRA28]

So is there a way I can dummy it up so it can run correctly without all the aircon sensors etc?

[CrUZida]

You'll have to look at the wiring diagram and see what sensors it looks at.

Most aircon sensors sre just NO or NC, so they are easy to fake.

[Sciflyer]

Yes it shouldnt be too hard, as you dont have the aircon system you will probably need to link a couple of pins at the fan ECU connector, as Gabe said they are labelled so a bit of trial and error with the engine running should get it

It sounds like it is just the aircon pressure switch input, just link the two pins/wires together

[cambelt]

I didnt connect my A/C pressure switch at all on my aristo 2J and my fan runs fast when its hot and needs cooling and slow when its cold .
I will add tho the fan runs a bit to fast say on a winters day with the engine warmed up if you pull up to park you can hear the fan moving a lot of air.
Dave

[TurboRA28]

So I found if I earth the AC wire on the fan ecu the fan slows down and seems to function as expected.

But I'm now in a similar situation with a hydro fan on a 1jzgte mx83, and this case it does have AC.. So where should the AC wire go? I heard the high pressure switch? But i'm not sure exactly what that is.

Thanks
Joel

[CrUZida]

If the MX83 is like the MA70, then there is a hi-pressure switch that turns the thermo fans on.
This switch will earth-switch a relay.

I'm not sure if the MX83 has the same setup, or whether its thermo's come on as soon as you turn the AC on.

[AndyTTR]

I had this same problem with my swap.

You need to connect the pins 'COOL' and 'HP' to ground for the fan to work normally (speed proportional to engine RPM + temperature).

COOL goes to the factory climate control ECU, HP goes to a pressure switch in the A/C high pressure line (open circuit when the pressure reaches a set threshold). When either of these aren't connected to ground, the fan will run at maximum speed.

Im not sure about the Cressie, but I needed to swap the 4 pin A/C pressure switch from the Soarer into the Supra for this to work properly. The Supra had a 2 Pin switch, the Soarer had a 4 Pin switch (it appeared to have two switch-over points).

There's a page on the cooling fan in the UZZ30 wiring diagrams posted by Mos here:
http://www.toymods.net/forums/showpo...&postcount=133

I reckon configuration of the wiring should be pretty universal for these things...