3-Pin Cooling Fan Issue

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TwitchTA

Commendable
Feb 23, 2016
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1,510
Hi,

I'm connecting up a few fans to a DC Adapter to augment the cooling system in my server cabinet.

I used an old test fan (3-Wire also) to test that i could do this then went out and bought 4 Corsair AF120 3-Wire cooling fans to connect to the DC adapter. The test fan worked okay with no issue, this being a dated fan i had lying around in my basement. The brand new Corsair fans LED's power up for less than a second before going out. The Fan's themselves inch a little but don't spin. I've checked that the amperage is correct. I have a 2amp DC adapter connecting up to 4 0.4 amp fans. I've also checked the fans 1 at a time to make sure it wasn't a faulty fan or that my wiring is incorrect.

Any ideas?
 
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I agree, that is really weird, but possible. As another test, can you take one of those new fans and connect it to a SYS_FAN port of a working computer to see if it works? Another potential source of a strong 12 VDC is an automobile battery using some temporary hookup wires.

If these fans are the "low noise" version, all that means is that they are designed to operate at lower speeds and noise levels (and lower air flow) than the "standard" versions, but they still should run easily on a 12 VDC supply. No, there is nothing you should have to do to change them.
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Paperdoc

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Oct 19, 2006
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Those symptoms certainly appear to indicate an inadequate power supply or a short circuit. Should not be happening, I agree.

Six thoughts:
1. Are you using an adapter that actually delivers 12 VDC, or is this an old "wall wart" from something else that actually delivers 12 to 15 V AC that still needs to be converted to DC?
2. I assume that, when you check the four Corsair fans one at a time, each does the same thing - fails completely to start. Correct?
3. Check wiring. The connections on those fans are: Black (Pin #1) is Ground, Red (Pin #2) is +12VDC, and Yellow (Pin #3) is the speed pulse signal you do NOT need or make any connection to.
4. Check your circuit setup. Those four fans should be connected in parallel to the power supply, not in series.
5. The fans come with "low-noise adapters" that can be inserted into the supply lines to limit the voltage to the fans, and lower their speed. You should NOT be using them.
6. You say you "checked that the amperage is correct". By that do you mean that you verified the specs (as you stated) should do the job, OR that you actually measured the current flow? If you measured current to each fan (including the old one) individually, and to the four new ones all together, what were those currents?
 
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T

TwitchTA

Commendable
Feb 23, 2016
4
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1,510


1) I bought the adapter specifically for this job and as such ordered a 12V 2000mA Adapter.

2) Thus far i only tried to set up 2 running parallel, and have only tested this on 2 of the fans. Both one at a time, and together.

3) I clipped the third cable down a little more than the others and didn't expose it's wires so that i knew the third was not one to be used.

4) For the moment i'm trying to get just the one fan working, though i know it needs to be ran in parallel.

5) I haven't added anything to the devices, however they are being sold as Low-Noise fans. Is this something i may need to remove?

6) I do mean i verified the specs, not that i have a voltage/amperage tester to hand.

I hope the info i provided illuminates this a little. Servers are getting a little hot! :)

 
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T

TwitchTA

Commendable
Feb 23, 2016
4
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1,510
As a followup. I hooked the fan up to a 9V battery. Male cable on the small male adapter. Second cable on the female adapter. This also caused the LED's to light up but the fan not to move an inch. At this point i'm of the opinion that somehow, the brand new fans (2 of them) are at fault.
 
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Paperdoc

Polypheme
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Oct 19, 2006
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I agree, that is really weird, but possible. As another test, can you take one of those new fans and connect it to a SYS_FAN port of a working computer to see if it works? Another potential source of a strong 12 VDC is an automobile battery using some temporary hookup wires.

If these fans are the "low noise" version, all that means is that they are designed to operate at lower speeds and noise levels (and lower air flow) than the "standard" versions, but they still should run easily on a 12 VDC supply. No, there is nothing you should have to do to change them.
 
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Solution
T

TwitchTA

Commendable
Feb 23, 2016
4
0
1,510
Thanks for your help, i continued working on it last night and worked out it was a classic ID-10-T error. The fan was barely nudging because i'd wired it backwards. I carried on testing with the 9V and switched around the cables and it worked. One of the fans was DoA which is what caused the confusion but the other 3 have been connected in parallel and work fine. Thanks for your help with this and with troubleshooting! Will mark you as my solution. :)
 
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