Sony PCV-RX490TV main fan now incorrectly keeps running continuously after being powered up from cold, with computer left completely idle. Fan used to run at full speed when computer was booted from cold and would immediately slow down to a whisper when Windows ME came into operation. Computer is working fine otherwise. There is no indication of overheating.
If one of you experts could explain in enough detail all the sensors and all the software used to control the fan speed, we should be able to easily diagnose the source of the problem. We have test equipment, including VOM.