Are the fan in lap top supposed to run always?

@Wordlinx (508)
October 14, 2009 4:00am CST
Laptop , cooling pad - In order to reduce the lots of heat generated during the long run of laptops, the cooling pads are employed. The cooling pad consists of two -four fans made of plastic (for low weight).They can be operated with the external power source as well as with the power from the laptop itself with the help of USB cable.They plays important role in the reduction of heat and hence to increase the performance of the system
I am not sure about this. My laptop fan is not running continuously. It will run for some time and for some time, it will not run .Because of this, my laptop always burning and I am not able to work. I have also cooling pad to reduce that.,But still the heat is not seems reduced.What is reason for intermittent running of my laptop fan? will there be any problem with the laptop? Is it necessary for the fans to run continuously?Are the fans are meant for continuous running? Please guide me in this. If I call the service engineer without knowing this fact, they may charge more by telling various faults with my laptop.