cooling fan adjustment?

[phatwurl]

my friend just purchased a 90 240sx and when i drove it last night, it was making a loud whirring noise when accelerating.
his mechanic told him that his cooling fan is spinnig too quickly and thus creates the noise. i have heard that the pilot bearing or somthing around the clutch makes a similar noise but his clutch was replaced, and the noise only happens when the accelerator is pushed so i dont think it is anything in the transmission.

i was going to try and help him fix this problem, but i do not know how to go about adusting the cooling fan or if it even needs adjustment, any help or suggestions would be great.

thanks