Sunday, February 6, 2011

Laptop Cpu Cooling Fan Not Working.....?


Yes, the fan, if plugged into the headers on the Motherboard, should be spinning. Even PWM controlled fans spin unless you manually disable them.

What kind of Laptop do you have? Usually, there's more than 1 fan header in Desktop Motherboard and You can always plug in the fan into a different fan header on the Motherboard to test the fan. but on Laptop motherboard there is only one header socket.
The one that is labeled CPU fan is to monitor and control it through the bios. If you fan isn't spinning when you boot up your Laptop, go into the bios, manually override the fan setting to spin at 100% all the time. If it doesn't spin, then there's a problem. Either your fan or the fan controller PWM circuit on the motherboard.

basically CPU fan has three to four pin connector/jack and different color wire.
fan connector placement is shown in the figures below:

Pin #Signal FunctionWire Color
1CPU Fan PWMGreen
2CPU Fan InYellow
3CPU Fan PowerRed
4GroundBlack

Pin Name Color
1 GND black
2 +5VDC yellow
3 Sense green
4 Control blue
CPU fans may use it 3-pin or 4-pin power connectors. 3-pin connectors are usually used for the smaller fans with lower power consumption and 4-pin connectors are usually used by CPU fans with higher power consumption. Fans and on-board fan headers are backwards compatible.
if now your fan not spinning even if it is proper plugged in on laptop motherboard, and your bios is fine
then first of all you should have to check fan with a 5v battery or you can use little high voltage battery like 9v but at this time don't connect fan with battery for a long time, that can damage fan.
to check a CPU fan with a battery just leave sensor pin free(no connected) and connect it's positive terminal with battery +ve point and GUN pin of fan connect with -ve of battery shown in the figures below if Fan start spinning that means CPU fan is ok now the problem has in your laptops motherboard




checking Laptop CPU Cooling Fan using a external battery






7 comments:

  1. dear what can i do if motherboard have problem..?

    ReplyDelete
  2. nice question.
    I will tell u all in my next post.
    i will show you how we can bypass the CPU fan supply circuit :)

    ReplyDelete
  3. i m also waiting dear for this solution ..
    i have hcl l19 notebook and i tried my best to repair fan prblm but couldn't fix the prblm frm motherboard

    ReplyDelete
  4. I`d be interested to know of possible ways of bypassing the fans power source.
    I have a machine where for some unknown reason the header is no longer supplying power although the fan itself is just fine.
    Looked for possible alternatives but there`s nothing obvious.

    ReplyDelete
  5. I have already explained that in one other post , please check http://repairing-solution.blogspot.com/2011/03/how-to-repair-laptop-cpu-fan-circuit.html

    ReplyDelete
  6. Keeping your computer always clean. We are talking the physical cleaning here we have to regularly do to our computers. Dirt and dust can easily build up on our computers fans and motherboards and this can reduce the ability of the computer to cool itself and function properly.

    Laptop Repairs Melbourne

    ReplyDelete