Damaged and noisy fan.
It took about 45 minutes. The guide was very helpful. It was kind of hard taking the keyboard on and off, but I am pretty dumb when it comes to computers. I damaged a piece putting the keyboard back on, but it doesn't affect the performance of my computer. After replacing the fan, it works perfectly now. My keyboard cover is just a little loose in areas.
Be careful taking the keyboard on and off. Keep your screws organized.
T6 Torx Screwdriver
Phillips #00 Screwdriver
MacBook Pro 15" (Model A1150) Left Fan