Replaced internal fans MBP First generation
Right fan was not running and that was putting more burden on the left fan and some processes caused the machine to get too hot.
This was my second experience opening the MBP so I knew my way to the inside. I replaced both fans and the left fan is harder to replace than the right because there are some tiny wires that pass over the left fan. A tiny strip wire that connected something to the main board came off and I had a bit of difficulty putting that back on. I had to use a magnifying glass. Had it not been for this little adventure it would have taken me about 30 minutes from shut down to restart.
I had a piece of paper on the table with the views of the case marked up where I kept various screw groups.
If you are replacing the fans have some kind of dust blower ready because the vents probably need a good cleaning too. I didn't have one but managed to clean them up by blowing on them.
Phillips #00 Screwdriver
MacBook Pro 15" (Model A1150) Left Fan
MacBook Pro 15" (Model A1150) Right Fan