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04 Cayenne TT
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Discussion Starter · #1 ·
Does anyone know if the electric fan on our vehicles is just an on/off switch? I have a variable speed controller laying around that I might put on if I could find this out. It's a leftover part from a truck I had. I also have two 14" aluminum bladed Permacool e-fans if anyone is working on a project.
 

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Where to place temperature sensor?

the head said:
Does anyone know if the electric fan on our vehicles is just an on/off switch? I have a variable speed controller laying around that I might put on if I could find this out. It's a leftover part from a truck I had. I also have two 14" aluminum bladed Permacool e-fans if anyone is working on a project.
hm, yes been thinking about variable fan controllers too.
It sounds like hell is loose when the fans start!
On my car theres two fans and both kick in at the same time..
Theres two outpouts from the ECU but only one is used..
So it should be possible to have both an extra variable fan controller and use the factory one as a security ..

Question is: Where to place temperature sensor?
 

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Discussion Starter · #5 ·
The probe for the controller I have (DC Controls) mounts in the fins of the radiator. It pushes into the fins.
 

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Discussion Starter · #7 ·
I'm to the point of separating the fans so if you want just one let me know.
 

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Discussion Starter · #11 ·
It just provides less load on the system. Rather than a sudden 20-30amp draw suddenly, it gradually increases voltage. This will make the motor in the fan and the charging components last longer since there is less shock load to them over the life of the components.

The only reason I'm considering it is because I already have one just sitting around. I did a mechanical to electric conversion on the fans on my old truck and needed a controller for those.

I should also point out that it makes things quieter since the fans come on and generally stay on at a lower speed - maybe 30% so you don't hear the fan running as readily. It also cuts down on the fan cycling on and off (another load rate reduction).
 

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I see. It sounds like a trade off between less "shock" to the electrical system and running the fans a lot more to get the same effect.

It's interesting that you find the fans noisy. I've actually never heard mine, even with the stock exhaust. The only way I can hear them is with the engine turned off in my garage.
 

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Discussion Starter · #13 ·
NahdaDamdyke said:
I see. It sounds like a trade off between less "shock" to the electrical system and running the fans a lot more to get the same effect.

It's interesting that you find the fans noisy. I've actually never heard mine, even with the stock exhaust. The only way I can hear them is with the engine turned off in my garage.
I've never heard the FXT fans at all. That was a general reference.

There is more wear on electrical components starting up than when they are running. You're also not running 100% when the fan is on and that helps with longevity too. So running the fan longer at a lower voltage is definitely better than having it start up and run full blast on each cycle. It also allows for better temperature control - less variance in the temps. That's not really a big deal for automotive applications but for cooling towers, aerial heat exchangers, and other industrial applications it helps things run more consistently in the process. I'm sure there is a lot of info on variable voltage controllers out there if you want to look in detail.
 

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NahdaDamdyke said:
It's interesting that you find the fans noisy. I've actually never heard mine, even with the stock exhaust. The only way I can hear them is with the engine turned off in my garage.
My fans are very noisy, but I have the older SF type Forester.
If I can find a controller thats works with whats there before, I will install.
 

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the head said:
I've never heard the FXT fans at all. That was a general reference.

There is more wear on electrical components starting up than when they are running. You're also not running 100% when the fan is on and that helps with longevity too. So running the fan longer at a lower voltage is definitely better than having it start up and run full blast on each cycle. It also allows for better temperature control - less variance in the temps. That's not really a big deal for automotive applications but for cooling towers, aerial heat exchangers, and other industrial applications it helps things run more consistently in the process. I'm sure there is a lot of info on variable voltage controllers out there if you want to look in detail.
The fan noise reference was from someone else's post.:) I'm more curious as to the detrimental effects of cooling or warming up the system slower than the factory set-up does in favor of preserving fan or electrical system components.
 

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Discussion Starter · #16 ·
You can set the fans through a probe to actually come on earlier. This way the fans don't kick on when (for example) 240 degF is reached. With the variable setup you could have it come on at 220 (for example) and the fans might run at 20% and if the car gets to about 230 degF then it's running at 40% and so on. Maybe that helps (?)
 
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