I've bought a cheap 12V 3-pin DC brushless fan a while ago. I didn't know much about why it had 3 pins instead of 2 when I bought it but now I know the third (yellow) wire is for measuring the fan speed. However, the fan does not spin when given the 12 volts between the black and red wires (ground and positive). It wobbles around a bit and then stops.

My first thought was that it's an AC 3 phase fan, but that makes no sense, first of all it clearly states "DC" on the fan, which could be a lie. Secondly, if it was an AC fan it would not wobble around at all when given 12 V, so what's going on here? Maybe I just bought a bad fan that doesn't work, maybe some of you guys know what's going on?

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    \$\begingroup\$ You have not provided enough information for anyone to analyze the problem and you don't appear to have enough understanding of brushless motors for anyone to help. I am voting to close the question. \$\endgroup\$
    – user80875
    Sep 13, 2020 at 13:09
  • \$\begingroup\$ What more information do you want? :S I don't know the model since it's a cheap chinese motor I bought like 3 years ago. I've described what I've tried to get it to run and what happens when I plug it in like you normally plug in 3 pin DC motors. \$\endgroup\$ Sep 13, 2020 at 13:30
  • \$\begingroup\$ So three years ago, it was a new item, advertised or marked as a 12V motor and you applied 12 volts to the black and red wires (red positive). It operated in a manner that you described as "It wobbles around a bit and then stops"? You did that again recently with the same result? You have done nothing else? Sounds like it was defective out of the box. \$\endgroup\$
    – user80875
    Sep 13, 2020 at 14:06
  • \$\begingroup\$ That's what I'm thinking, but maybe there's something I don't know about about 3 pin fans and hence why I'm asking here. Maybe someone else has had a similar problem and it's not a defect part but a different control mechanism than a regular 3 pin fan. \$\endgroup\$ Sep 13, 2020 at 14:25
  • \$\begingroup\$ If you connected it wrong, or if the wires do not have the expected color code I don't think the motor would run at all. I think it would be difficult to impossible to repair. \$\endgroup\$
    – user80875
    Sep 13, 2020 at 15:17

1 Answer 1


The fan was simply broken :(


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