Lenovo T61 CPU fan stopped working

[linefeed]

Hello everyone.

System boots and works normally, but when laptop is working, it becomes warm enough but CPU fan doesn't rotate.
On power-on CPU fan runs for a second and then stops.
I disassembled the laptop, removed and checked the fan - it's rotating when 5V is applied to it.
DC 5 volt on fan connector appears for one second after laptop power-on (and the fan rotates then) and then disappears. Fan doesn't rotate even after I ran the laptop for half a minute without heatsink attached and CPU became hot enough.
What can be checked in this situation?

[theterminator93]

Have you tried using TPFanControl and manually setting the fan speed to see if it responds?

[RMSMajestic]

On my T61 the fan only start to work at some 60 Celcius

[linefeed]

Well, it fixed itself. Maybe it was blocked with dust initially or was not hot enough to turn on. After reassembly it starts rotating when it gets warm enough.