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Old 08-22-2018, 11:11 AM   #1
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Cooling fans hi & lo

Had a bad resistor. Fan would not function at low speed. Hi speed, no problem.

So after about 3 years, I finally attack this and replace the resistor. I started the car up and just let it idle while I was cleaning up the garage. Once the temp needle hit the middle of the zero, both fans kicked on. Yippee!
Then I thought about it and how do I know that was low speed? I don't have an A/C button to press anymore. (Another issue, don't ask.)
I guess I will have to take it out and beat it up some to get the temp high enough to trigger the hi speed.
My question is, anybody know what temp triggers the hi speed?

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Old 08-22-2018, 02:48 PM   #2
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My question is, anybody know what temp triggers the hi speed?
I believe that 216F triggers the high speed mode. It can sometimes be hard to get the coolant temp that high. Another fairly easy option is to jumper the fan relays to test both high and low speed operation.

I would say that if the high speed is engaged, you'll know it. Sounds like a hurricane under there and often dust and debris will be blown up and around the front of the car if the car is standing still.
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Last edited by thstone; 08-22-2018 at 02:54 PM.
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Old 04-06-2019, 11:47 AM   #3
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resurrecting an old thread, ope some of y'all can help me for a moment?

I want to be sure I understand the cooling-fan system correctly, before I go chasing its' demons.

IIUC: there are TWO fans, one on each side, which run at TWO Speeds, depending on which relay has triggered them, right? So if my low-speed fan function is not working, that makes NO difference, once the Hi-Speed is triggered, right?

Using the durametric, I've triggered the low-speed fans, and neither side runs. I can feel both relays moving, but to be sure, I swapped with known-to-be-good relays; no change. When I trigger the Hi-Speed fans, both run.

So: if I've correctly understood the other posts about this, that means I've got bad resistors on BOTH fans? is that common, for both to fail? Or does this sound like a common-point-of-connection has failed?

Where are the resistors located, physically? Do I need to pull the bumper-cover to get to them?

It's also my intent to wire-in a switch to run the fans manually, for hot days at the racetrack. How have y'all done this (those who have): Have you tagged into the wires at the relay?
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Old 04-06-2019, 12:29 PM   #4
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i just checked schems for you; presume your car is 2000 or later?

each fan has two relays (total 4 for the front) - high speed each side, low speed each side.

common ground on each side, common power each side, so no reason any kind of failure on one side would impact the other. just unlucky?

i could email schems to you if your email can handle 22 MB (not sure mine can, honestly)?
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Old 04-06-2019, 03:24 PM   #5
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i could email schems to you if your email can handle 22 MB (not sure mine can, honestly)?
Oh you're a good man, TRK! ;-)

Yes, my car is an '03 S.

I'll PM you with an email address.

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Old 04-07-2019, 10:07 AM   #6
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The resistors are in front of the radiators clipped to to the air inlet shroud at the bottom. It is fairly common for the resistors to fail and that causes exactly the problem you describe.
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Old 04-08-2019, 05:21 AM   #7
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The low speed resistors are clipped just in front of the front wheels. If you search there are industrial Resistors you can replace them with that are around $10 each. The OEM's are much, much more and either way you have to cut wires
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Old 04-09-2019, 05:27 AM   #8
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I used the info on Pedros board. Made a jumper and removed the relays to test HI/LO function. Found my right fan wasnt working at all.
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Old 06-05-2019, 02:19 PM   #9
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The low speed resistors are clipped just in front of the front wheels. If you search there are industrial Resistors you can replace them with that are around $10 each. The OEM's are much, much more and either way you have to cut wires
Any idea where these $10 resistors can be found?? output?
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Old 06-06-2019, 01:29 PM   #10
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Any idea where these $10 resistors can be found?? output?
here you go.
https://www.amazon.com/dp/B008MLL3JQ/?coliid=IKDDF8ZS9NKPS&colid=UVT3NPLJ4SQQ&psc=0&ref_=lv_ov_lig_dp_it
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Old 06-06-2019, 11:32 PM   #11
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Thanks!
So I guess the 100watt 0.5 ohm is the way to go..?
So many seeming to go bad maybe this should be a sticky..
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Old 06-07-2019, 04:17 AM   #12
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This is where I bought from

https://www.mouser.com/ProductDetail/ARCOL-Ohmite/HS75-50R-F?qs=I%252BtR9uIPP5X6A6agKiVp3w%3D%3D&gclid=CKn4w6af1-ICFRqUswodd5sP7Q

Time will tell how well these last
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Old 06-10-2019, 10:27 AM   #13
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Thanks for the links!
The first one reads 100watt 0.5 ohm
The second one reads 75watts 50 ohm

Is this critical and wondering what the oem specs are?

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