20 mins & no problem
20 - 30 minutos
the right fan in my MBP15 3,1 stopped working so I had to replace it
Replacing the fan is easier than replacing a hard drive. It took me longer to open up my MBP than to replace the fan. I took the 3 screws out and disconnected the plug. Dropped in the new fan, put in the screws and hooked up the plug.
watch which side is up on the plug before unhooking it. That's the only think that slowed me down putting the new fan in. Good luck