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karinvail

cooling fans

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the previous owner of my car put a switch in on the dash for the electric fan when it quit working on it's own. I don't like the idea of a fan on a switch because things like that can be forgotten to turn on/off, especially if someone borrows your car and isn't used to worrying about stuff like that. I have access to a parts car with a mechanical fan that is on the water pump (this fan looks like it has some sort of clutch in it because it spins even if the water pump isn't spinning - if that makes sense). Can I cull the electric fan and just use the mechanical fan off this other car?

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What are you thinking? The clutch fan takes a bit of engine power to run, the electronic fan switch in the rad or the relay are bother some. You have got the bling-bling of subbie fans, that's right it's all about the switch! If the runs even with the the key out, well then you need to do some rigging but otherwise leave it.

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The electric fan is always connected to +12V and turns on when the temperature switch in the radiator closes the circuit to ground. Often it stops working because the radiator itself is not grounded. Check to see that the little ground wire at the top of the radiator is still there and connected since that might be the cause of the failure. It also helps to insure that the temp switch is still connected to the cars wiring harness. I know this doesn't answer your question but it might resolve your problem.

the previous owner of my car put a switch in on the dash for the electric fan when it quit working on it's own. I don't like the idea of a fan on a switch because things like that can be forgotten to turn on/off, especially if someone borrows your car and isn't used to worrying about stuff like that. I have access to a parts car with a mechanical fan that is on the water pump (this fan looks like it has some sort of clutch in it because it spins even if the water pump isn't spinning - if that makes sense). Can I cull the electric fan and just use the mechanical fan off this other car?

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I too had my electric fan quit working. It was the thermoswitch on the radiator that caused it. I pondered tossing a switch in the mix, but nixed that idea for the same reasons you don't like it.. I forget things.

 

So instead, as a quick fix I wired in a new circuit and relay so the fan comes on with the key.. I found it actually works quite well that way and haven't found a good reason to go back to the original configuration.

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Here's some solutions:

 

  1. Buy a new thermoswitch for the radiator and wire it back up like it was stock.
  2. Wire the current fan/switch into your ignition circut so it automaticly shuts off if you or anyone else leaves it on accidently.
  3. Leave it how it is, don't forget to shut it off, and remind ppl who borrow your car to turn it on and off.

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so a thermoswitch is the main reason that the electric fans quit working?

 

 

Why is the electric fan better than the mechanical fan?

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Thermoswitch, bad grounds, bad connection to the thermoswitch are the three primary causes. Electric fan is better because it only runs when needed and doesn't rob power from the engine when it's not needed.

so a thermoswitch is the main reason that the electric fans quit working?

 

 

Why is the electric fan better than the mechanical fan?

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well, I guess I should start with re-attaching the wires back to original and add a ground (there isn't one that I can see). Where do I ground to/from?

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The thermo switch grounds back to the wiring harness (thats why it has two poles).

 

And there are my thoughts on the electric/mechanical fan debate (from this thread).

http://www.ultimatesubaru.org/forum/showthread.php?t=21917&highlight=electric+fan

 

The electric fan is actually the stock one and the mechanical one was added to the A/C cars. If you don’t have A/C you should be fine with one (or two) of the stock type electric ones. If you do have A/C (and use it) I’d stick with the mechanical one, or if you do want to go with twin electric get a high flow aftermarket one, I don’t think the stock electric one can pull near the air that the mechanical does, just look at the size and pitch of its blades.

 

The amount of power saved buy switching from a mechanical fan to an electric is a bit of a myth, if the mechanical clutch fan is functioning properly it only pulls when the rad is hot and needs it. The electric fan requires power too, and its power is subject to two electo-mechanical conversion (alternator and fan motor), both of which have about a 70% conversion efficacy, so the electric one requires about 50% more input power for the same output.

Gary

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Sometimes there is only one pole in which case, the radiator needs to be grounded properly. I don't know which models have which, but I've seen it both ways.

The thermo switch grounds back to the wiring harness (thats why it has two poles).

Gary

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ya but the only other thing is the fact that the alternator is turning regardless of any load put upon it, it makes power with or without the fan on. no extra power is required form the enigne to spin alt. faster or slower, only the voltage regulator sees the punishment. i say screw mechanical clutch-type fans, rob power and they just plain suck in my opinion, wire the fan into your ingition system to the ON position, you shouldnt have any probs with that.

 

 

 

~Josh~

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Regarding the power; it's certainly not a lot of power robbed from the engine or the alternator, but it takes energy to spin that little puppy around and it's got to come from somewhere. I wasn't trying to start a pissing contest here, just answering a query...."what's the difference?"

 

As to the second part of the question, here's a pic from my Brat which has the single pole thermoswitch on the side of the radiator. The original is usually a skinny 18 guage wire or less. Even tho there's negligible current draw here, I would suggest replacing it with about a 14 guage or larger; they last longer.

 

showphoto.php?photo=4663&sort=1&cat=500&page=1

 

Okay, what did I do wrong? I uploaded the pic into my photo gallery and then attached it using the URL from the picture, but that gave me the stupid red X:banghead:

 

Try this: http://www.ultimatesubaru.org/photos/showphoto.php?photo=4663&sort=1&cat=500&page=1

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no extra power is required form the enigne to spin alt. faster or slower, only the voltage regulator sees the punishment.

~Josh~

 

Absolutely not true, I’m not going into all the engineering and physics but I promise you that the power required to spin the alternator increases proportionally with its output. Power out is equal to power plus losses. 1hp = 745.7watts, with a nominal 14volt system that’s 53amps. The alternator is at very best 70% efficient, so for 1hp output you need 1.4 hp input and that doesn’t account for mechanical and belt losses or the conversion back to mechanical energy fan motor (again around 70% would be very good). In the end to get 1hp output at the electric fan you would need at VERY least 2hp at the alternator.

 

Or another way to look at it… with a stock 55amp alternator (output), the most power you could get at the electric fan is .72hp if it consumed all 55 amps.

 

There is a reason most cars still come from the manufacturer with a mechanical clutch fan.

 

Just one point of view (supported by the facts)

Gary

 

P.S. I didn't know that some EA81s had a single pole thermo switch... I stand corrected.:) They must have made the change on the EA82s, as most of them have radiators with plastic tanks.

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I removed my pulley driven fan and replaced it with an "aftermarket" thermostatic energized electric fan a few years ago. I was hoping for some xtra hp's out of the deal....nah. But I got the unexpected bonus of at LEAST 5 mpg more!! (I had a 60 mile each way commute at the time, kept close track of my gas mileage)

 

I wired an "on" light for the fan so I know when its energized. I've noticed the fan rarely comes on during the winter (cooler) months....usually only energizes in HOT weather while sitting in slow traffic....This just tells me this pulley driven fan was rarely "needed"...hence a waste of engine energy- regardless of engineering facts of what the electric fan draws when used....

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But I got the unexpected bonus of at LEAST 5 mpg more!! ...

 

NOW you're talking - saving gas is a GREAT reason not to have the mechanical fan - thanks for that! I wasn't so much worried about lack of power for my 'grocery getter', but I sure am worried about saving money!

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Of course another reason to ditcht he clutch fan is that they are a real PIA to get on and off when doing engine work up front. (I've got big hands.) I'm going for it.

Pyro

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