fan running at slow speed almost always; laptop overheating

Hardware and OS details in signature.

The last couple of times that I have opened up my laptop to clean and lubricate the fan, the fan has not behaved properly.

The fan would get stuck at a slow speed, almost inaudible. Sometimes, just after booting, the fan would run faster for a few seconds, then go back to the slow speed. Temperatures would get rather high; in stamina mode temps would reach 50 deg C in idle condition; up to 80 deg C just browsing the internet with Firefox and Chrome windows open. An antivirus scan would cause the laptop to shut down.

Putting my ear close to the air vent I could hear the fan rotation, not at the expected constant speed, but speeding up and slowing down cyclically at about 20 times per minute, the speed varying between a very slow speed and a somewhat higher but still slow speed.

Needless to say, speed mode was totally unusable. The laptop would overheat and shut down, even on idle. No gaming.

The last time it happened, running a popular bittorrent client (qBittorrent) suddenly and inexplicably restored normal behaviour. This time, that didn't happen. After struggling on and off with this very annoying issue for over a week, I started to dig around the VAIO utility folders. As I opened the C:\Program Files (x86)\Sony\Setting Utility Series folder and scrolled down, the fan suddenly started functioning properly.

The picture below shows the temperature graph of OpenHardwareMonitor. See the high temperature while just browsing, and then the rapid cooling off as the fan suddenly decided to kick in.



Could someone please tell me what is going on? I had started looking to buy a new laptop (I am busy with some very urgent work). I particularly want to know what to do if it happens again.

 

Not sure what to suggest. Sounds like your fan may be functioning intermittently and that it changes when you do certain things on the laptop could be completely coincidental. I guess you've tried the obvious things like changing the fan speed in VCC to "performance" or "cooling".

 

Yes, that was the first thing I tried. It only happens after I open the laptop and change the grease on the fan shaft, and I do that only when the laptop starts shutting off due to overheating. Now that it is working, I'm good for several months until the grease on the fan shaft wears off and the fan starts siezing again.

Maybe I should do preventive maintenance of the fan, and not wait until the laptop starts shutting off due to overheating. I'm suspecting that Windows notices that the embedded controller that controls the fan speed is misbehaving and prevents VCC and Vaio Power Management from communicating with it. Something similar to DEP.

 

Just an aside, the temp on my VPCZ1 never really drops below 50C when idling (and has always been like that). However, it doesn't get particularly hot when I'm browsing etc. and has never shut off because of high temps (though I don't push it too hard). It's never been opened. So my only point is that I wouldn't be too concerned about it idling at 50C.