I'm currently having problems with the fan behaviour of my Toshiba Satellite A300D-18A under Mint. Since it's a common problem with Toshibas, I was expecting to find a sollution quickly, but no luck so far, even after searching for a few months.
To put it simple, everytime I start Mint, the laptop fan runs at about half-speed (unfortunately lm-sensors can't detect my actual fan speed, so I can't give you exact numbers) all the time, and doesn't come off. Sure it keeps my laptop cool, but the fan is annoying me too much. Suspending and resuming seems to solve the problem, but not completely: there the fan seems to only switch between either off, or full blast. This makes the temperature float between 55º and 70º Celsius. Also, tried Ubuntu, same problem.
Most common solution I found was the "acpi_osi=Linux" one. It didn't work for me. Tried the somewhat old Omnibook module, configured as "fan=1" and "fan policy=1". Still no luck. Even tried the ATI proprietary drivers, as someone suggested, and nothing.
So, I'm starting to lose my hopes, I really wanted to keep using Mint, but not only this is not healthy for the fan, it also gets annoying after a while.