How do you know if the cooler is working properly?

Question

linux

Took my laptop in for cleaning.
I noticed that the cooler is now barely audible. And the temperature is almost always at the same level (about 55-60 degrees), under any load.
How do you know if the cooler is working properly? rpm, voltage, etc. How to check it? I do not want to re-carry the laptop for repair, if it turns out to be in vain.
Ubuntu 16.04

Answer 1

1) Any laptop with a fan in daily use requires dusting once a year. If there are animals - once every 3 months.
2) Run the 7zip archive test and see the CPU temperatures after 15 minutes. If they are up to 70 - then everything is fine, if from 70 to 80 - more or less, if more than 80 - problems. I think room temperature is 25 degrees.
Z.Y. Dry thermal paste or a large amount of it may also be to blame for overheating (they could flop heartily at the factory according to Chinese tradition).