Why is the cooling system not working properly?

Question

macbook

I recently upgraded my 2014 MacBook Air to a 2017 version. On the new laptop there was a problem that was not on the previous one. The cooling system periodically starts up - the cooler starts to work somewhere at medium speeds. But at this time there are no reasons for this, nothing heavy on the laptop is running.
I use iStat Menus and at the time when the cooler starts to make noise, the rpm value shows incorrectly - around 600. If you try to set the rpm manually in istat, the cooling system does not react in any way.
Over time, everything returns to normal, the speed drops to ~ 1200 and the ability to change the speed value returns to istat.
Reset SMC did - did not help.
iStat and deleted and changed versions - did not help.
Maybe someone has a version of how to fix it?

Answer 1

Replace the cooler - the signal from the tachometer disappears and the system goes into error, twisting the speed to the maximum.