Julia, While computer apart do not just clean the fan, clean every thing you can using a can of compressed air, this will ensure proper cleaning and reduce damaging heat build up on internal components. I will post links that will help you see how to disassemble laptop and instructions on cleaning. Check the attached links,instruction and guides, Good luck.

I hope this helped you out, if so let me know by pressing the helpful button.

http://www.howtogeek.com/194479/how-to-c...

https://www.youtube.com/watch?v=03yPJT9J...

http://www.basicspc.com/?p=3447