Fan Replacement - 17" MacBook Pro (2009)
I noticed a while back that when watching a movie or using my MacBook for an extended period of time the fan on the left side would begin to get very loud and the left half of my MacBook would get very hot. I downloaded an app called "iStat" which monitors CPU usage, internal temps, fan speeds, etc and discovered my left fan was running well over 5000rpm, while the right fan wasn't working at all.
I ordered a replacement fan from iFixit, as well as the tools needed to complete the job. The order arrived within a few days, and I followed the simple step by step guide to replace the fan. It took around 10 minutes, despite the fact that this is my first experience taking apart and repairing any sort of laptop.
Follow the step by step guide and you should be fine.
MacBook Pro 15" Unibody (2.53 GHz Mid 2009) or 17" Unibody (Early/Mid 2009) Right Fan