The system fan is always spinning in my Tecra Z40-C-106, is this expected behaviour or is my laptop faulty?

I've tried installing all system drivers and turned on Eco mode but the fan never goes below about 3100rpm.

Tried BIOS setting cooling method to power saver, no change.

Tried setting the cooling method in Toshiba Power Saver settings (in Windows power settings) to power save, no change.

Tried speedfan utility, didn't find my fan controller.

Tried notebook fan control utility but there are no configurations for the Tecras and I didn't manage to find anything useful when probing the EC registers, the fan does not seem to be controlled by the EC.

Read about someone who supposedly manages the fan through ioctl calls to tvalz.sys but that is above me at the moment.

I can force the fan to spin faster when applying load to the CPU to warm it up so the temperature compensation seems to work but the fan never goes below those 3100rpm when the system cools down again.

It's quite annoying to have to listen to that little high pitch fan when the laptop is running cool anyway most of the day....

Any ideas?