I am a VAIO FZ38M owner and I have the same issue as you have.
My fan is silent when I start the laptop from fresh (powered off for some hours) and starts spinning and making noise after a (very) few minutes.
However, please give me some more details.
-Do you feel it noisy in a Office or Home environment ?
In my Office the Airconditioning is significantly louder than the laptop fan noise.
In my home room, this noise is the main noise and is very annoying.
-Is there any task running in the background (Antivirus check ) ?
Try to open Windows Task Management (CTRL+SHIFT+Esc) and go to Processes (click on Show processes from all users) and check if the System Idle Process is taking more than 90%.
-Check your power plan
(Click on the battery icon near the clock and try to use VAIO Maximum Battery or try to customise your current profile)
I posted a similar post here one year ago when I bough my laptop but there where no solutions for it. 😞
