Sorry for all of the updates, but I have since moved that kext back and the fan almost immediately started back up. So I opened System Preferences > Keyboard and unchecked the "Adjust keyboard brightness in low light" checkbox, then turned the backlight completely down/off (the F5 key on MBP keyboard). Again, I'm almost completely fan-free, only having a few seconds of fan activity when Photoshop opens, etc. This way, when I need to, I can turn the backlight off and then back on when I need it, without having to move the kext back and reinstalling. I'm hoping that, like 10.6 and 10.8, 10.10 will be a better experience and my Mac won't go back to running out of control. I don't know if this will work with any other laptop, but if you have a light sensor and use auto adjusting with your laptop's keyboard backlight, try these steps first, before moving ANY kexts. I should have said before: MacBook Pro 6,1 (mid-2010), running OS X 10.9.2 (Mavericks).