I have two T35696-HP cooling fan motors from an HP C7000 server rack. I am going to use the motor/fan with a DC source outside of the normal capacity as a cooling fan for a server. Therefore, I am not going to be using the existing circuit board that controls the motor.

I have not been able to find any schematic for the circuit board for this cooling fan. Because of this I am having difficulty knowing what wires coming out of the fan motor do what. There are only three (3) wires coming out of the fan motor. Blue, Yellow, Red. I am assuming the Red wire would be power but I would expect to see a Black wire for ground. There is not one.

T35696-HP wire connections

Since the fan is wired to the circuit board and the board is plugged into a computer slot, I am running under the assumption the ground was somehow handled within the circuit board itself. If that is so, could I simply ground the motor housing if running directly to a power supply?

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I plan to wire this motor up to an external 12 V power supply and a controller that will control the speed of the fan. I would like to know what wires to use for 'power', 'ground', 'control'.

  • 1
    \$\begingroup\$ Can you upload a photo of the board? Someone may be able to identify the purpose of each wire from the image. \$\endgroup\$ Commented Mar 22, 2018 at 15:43
  • \$\begingroup\$ Are you sure this isn't a 3-phase induction motor? newfound-energy.co.uk/electrical-three-phase-wiring-colours \$\endgroup\$
    – user16324
    Commented Mar 22, 2018 at 16:04
  • \$\begingroup\$ DC source outside of the normal capacity ... what does this mean? \$\endgroup\$
    – jsotola
    Commented Mar 22, 2018 at 19:20
  • \$\begingroup\$ I have added two pics of the fans. This is a 12V 16.5A cooling fan from a C7000 HP server rack. \$\endgroup\$
    – RVbySDI
    Commented Mar 22, 2018 at 19:23
  • \$\begingroup\$ jsotola - What I meant was I intend to run the motor as an electric ducted fan for an R/C model. I do not plan on using the existing circuit board that is currently controlling the motor. \$\endgroup\$
    – RVbySDI
    Commented Mar 22, 2018 at 19:25

1 Answer 1


Just use a brushless motor ESC (electronic speed control). Black wire not needed. I believe the ESC needs to be at least 30 amp or higher. I will be using a 30amp.

  • \$\begingroup\$ Not sure how to add pics to this site but I hooked mine up with 30amp brushless esc. to a 12v PS and it works great. All three wires on my esc are the same color so I just hooked them up in no specific order. I believe order of wires to motor does not matter to esc. I have my esc plugged into a servo tester so that I can control it without having to use my rc transmitter and a receiver. Works great. I hope this helps. \$\endgroup\$
    – Drew
    Commented Apr 1, 2018 at 1:33
  • \$\begingroup\$ You upload images using - uhm - the image upload button on the editor toolbar. There are restrictions on new users until you have some rep. Upload the image and post the link and someone will fix it. \$\endgroup\$
    – Transistor
    Commented Apr 1, 2018 at 13:29
  • \$\begingroup\$ @Drew order of wire in an ESC only matters for which direction it spins. If you find that a BLDC is spinning the wrong direction, then swap exactly any two of the three motor wires and it will reverse direction. \$\endgroup\$ Commented Aug 22, 2020 at 17:22

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