Fans running despite lack of apps using much energy?

[bearinthetown]

In my MacBook Air 2018 I experience fans randomly running as if I was doing something heavy, while I have one Chrome tab open and iMessage app, for example. Also, Activity Monitor doesn't show any suspicious CPU usage. Are there any processes that could be running, but not reported in Activity Monitor? Or is it a faulty battery?

 

[chrfr]

In my MacBook Air 2018 I experience fans randomly running as if I was doing something heavy, while I have one Chrome tab open and iMessage app, for example. Also, Activity Monitor doesn't show any suspicious CPU usage. Are there any processes that could be running, but not reported in Activity Monitor? Or is it a faulty battery?

If your battery is dead or defective, then yes, the computer will throttle itself and the fans will run.

 

[bearinthetown]

I had my battery replaced two weeks ago or so. It has just 6 cycles. And it doesn't even last 5 hours. I feel powerless, this service keeps replacing my battery causing new problems every time.

 

[Toutou]

You could install one of the temperature reading apps (I use Macs Fan Control, but there are others) and check if the fan ramping up is a (correct) response to a temperature hike or if it really happens on its own.

Are there any processes that could be running, but not reported in Activity Monitor?

Shouldn't be, IF you have Activity Monitor set to show all processes (menubar, View -> All Processes).

There could also be processes that use the GPU, but don't use the CPU that much, so you miss them when looking for high numbers in the % CPU column. There's a % GPU column (not sure if its visible by default) that you can check. A badly written animation or ad on the web can make the GPU heat up quite a bit.

 

[chrono1081]

while I have one Chrome tab open

That's probably your problem (not even kidding). Chrome is just not a good browser and hogs system resources. Try another browser (ensuring Chrome is closed) and see if you still get the fans kicking on. Also it depends what is on said page. Web pages have so much junk in them these days that operates in the background.

Also I'm assuming you're not using your laptop on a soft surface (like a blanket) because if you are, that will cause the fans to kick on too.