Posted 02 July 2011 - 01:50 PM
The Normal reason for the fan racing is that the CPU is running hot.
Some laptops the fan is easy to get at and makes it easy to clean the heat sink. Some if you pull the keyboard you can see the fan and then blow out the heat sink.
Some you need to remove the top cover....
Keep in mind that you need to blow the air in from the outside to reverse the airflow. Blow back and forth until the heat sink is clean.
The make and model of the laptop would also help with more targeted directions. Having the Fan race like that is shortening the fan life and the extra heat is shortening other components life too.
Another cause I've seen, On my own Toshiba at that, is a problem with the heat pipe that brings the heat from the CPU to the Heat sink fins.
Mine was spotless but the fan kept racing up and down. Changing the heat sink assembly cured that. Fortunately the part was cheap from Toshiba as a repair center and I have the skills to fix it.
One thing to do is not keep using it as you are shortening life on many parts that way.