Laptop Fan, blown up?

Hi all,

I've got a problem with my laptop, an omnibook 4150. It's already quit old, but it does what I want it to do. The problem is that the fan isn't working properly. It goes on when the cpu reaches a temperature of 85 celcius (!), which is too hot. Speedfan can't acces it, but it does work when booting, producing the sound of a jet.
-Battery is dead, so it's always on direct power source.
-DVD player is out aswell
Don't know if this will have affect on it, but I 'm not the expert here  .

Thanks in advance!