Whats up with my hydrofan?

Tim

regular member
Oct 16, 2006
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CA
Just wondering what you guys think. When ever my car is running the hydrofan is always spinning pretty fast. From the second I turn on the car the fan speed does not change. The car does not get hot at all, it actually runs very cool but I know that the fan is supposed to very speeds depending on the temps. I am positive that the wiring is right. What do you guys think? Bad hydrofan ECU?
 

TurboFreak

NOBAMA
Jan 22, 2006
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EDIT: I'm an idiot and did not bother to look at his avatar...soo nvr/mnd

Mine always ran the same speed I thought from the moment I turned the car on. Sure its not supposed to do that?
 
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Tim

regular member
Oct 16, 2006
272
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CA
Yes, I installed a brand new OEM thermostat, but from what I know the fan is supposed to vary speed depending on water temp. That is why it uses the temp sensor on the radiator and the hydrofan solenoid. The way it works now is fine, but I am afraid of maybe burning out the fan.
 

The Reaper

Single, and lovin' it!!
Jan 10, 2006
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Florida
do you have a 1JZ radiator or a 7M radiator?

there is a sensor that goes down on the bottom of the 1J radiator near where the Radiator drain plug is that regulates the Hydrofan

when its cold its spins slower....when its hot it cranks out some SERIOUS air.

if you have a factory 7M radiator the sensor will screw into the drain plug hole. stock replacement radiators drain plugs are too small.

its fine that it spins at full speed wont hurt anything. i have the temp sensor and hydrofan but i have an aftermarket stock replacement so the temp sensor wont screw into it.

EDIT:: damn i typed all this out without reading yur last post. LOL

maybe your sensor is shot???
 

bigaaron

Supramania Contributor
Apr 12, 2005
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On my old car, the fan control solenoid on the pump stuck and it ran on high for a day or two. Then before I had a chance to really look at it, it spontaneously fixed itself and worked flawlessly for two years. :dunno:

If the solenoid or fan control ecu is the problem we can take care of it in a few minutes. Check the sensor in the bottom of the radiator also, make sure the wires are connected and it's not broken.
 

Ken

New Member
Apr 6, 2005
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not to hijack the thread, but do the wires going from the fan ecu to the a/c high/low pressure switch and a/c amplifier have anything to do with controlling the fan speed? are they of any importance if you have ac installed???

I've been trying to find the answer to that question for over a year now.
 

bigaaron

Supramania Contributor
Apr 12, 2005
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itr.00-1282 said:
not to hijack the thread, but do the wires going from the fan ecu to the a/c high/low pressure switch and a/c amplifier have anything to do with controlling the fan speed? are they of any importance if you have ac installed???

I've been trying to find the answer to that question for over a year now.

I believe that the wires coming from the ac system are to tell the hydrofan ecu to increase the fan speed when the air conditioning is on. The ac system makes a lot of heat, so the fan needs to run at a higher (or full) speed all the time when the ac is on. The temp sensor at the bottom of the radiator is so the hydrofan ecu can automatically regulate the engine coolant temperature.
 

Tim

regular member
Oct 16, 2006
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CA
I am not running AC on my car. I checked the temp sensor and wiring and they look good (not broken). what do you think Aaron? Do you think that maybe the solenoid seized?
 

bigaaron

Supramania Contributor
Apr 12, 2005
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Tim said:
I am not running AC on my car. I checked the temp sensor and wiring and they look good (not broken). what do you think Aaron? Do you think that maybe the solenoid seized?

You can check the inputs on the hydrofan ecu with a multimeter andmake sure there isn't voltage where there shouldn't be. One way to tell is to unplug the solenoid and see if the speed doesn't change.