HELP, fan start then stop after few seconds.

Azidaha

Estimable
Apr 7, 2014
2
0
4,510
Hello,
I did reassembly two of my laptops, to clean them from dust and other junks inside. They are an old Fujitsu Siemens and an old Toshiba A300.
What I did was, remove the heatsink and fan and clean them both. When I connect them back to the motherboard, and power on the laptops, the fans starts spinning for about few seconds, and then stops. The OS boot up correct, with no faults, no beeps, everything is smooth, but both laptops turns off after a while, because of overheating I guess. The fans, DOESN'T start anymore. They spin only when the first press of the power button is released, and for the next few seconds 3-4 seconds.
I did clean them with compressed air, and I have connect them propper.
I think, that I miss something somewhere, but the question is what and where.
Please, help guys, because on other side, the second laptops is my wife's one, and she's gonna kill me :)

All the best,
Azidaha

PS. I have tried a CMOS reset, with battery removing, but it didn't change anything.
 

Azidaha

Estimable
Apr 7, 2014
2
0
4,510
They start spin, and spin proper as they should.
The problem is that they stop soon after they start.

Same things happen with both of them. That's why I think more like I did miss something...
 

techgeek

Distinguished
Apr 11, 2004
175
0
18,710
Well its normal for the fans to start initially and then stop shortly afterwards. Once the motherboard begins to monitor the CPU (and GPU if it has a discrete GPU) if the temperature is low enough, it will slow / stop the fan. Once the temperature rises though, it should start the fan again.

As for spinning, even with the motor damaged, it could spin initially, but as the motor heats up due to excessive friction, it will eventually stop. I have seen this behavior many times in fans.