You might need to edit /etc/cpufreqd.conf
This is all that I have in mine.
You can get a list of policies and frequencies available from;
For some reason cpufreq mistakenly thinks that my system is always on a battery. Which is odd since it's a desktop.
So it's possible that it's mistaken about your laptops battery/ac status too.
“Gosh, you've... really got some nice toys here.”
LinuxMint 15 (Olivia) XFCE 64bit • AMD Sempron 3100+ • 2GB DDR 400 • NVidia GT240 512MB