Why is the laptop cooler not working at the proper speed?

Question

laptops

I have a dell inspiron 5558 laptop
. Yesterday I cleaned and changed the tempo paste. Thermal paste Arctic cooling mx-4.
For a long time there has been a problem of the following nature.
Sitting at the laptop, I begin to notice that the top of the laptop (keyboard) is too hot. I lift the laptop, put my hand under it, and there is heat, hell. The bottom of the laptop is hot, the table is hot. I put my ear to the cooler, it doesn't work. The cooler is working and connected.
Recently glued new pads on the bottom of the laptop to lift it up. Now the distance between the table and the laptop is 5mm. From the factory, this distance was less.
Now the most interesting. When I notice that the laptop is hot, I turn it over. As it were, on the contrary, that is, the laptop lid lies on the table, as usual, the case lies and the case is located like a lid. Well, that is, upside down. I wait about a minute and after a minute the cooler accelerates to maximum speed and the temperature instantly starts to drop. It seems that only in the upside-down position, the laptop understands that it is hot and needs to cool down.
What could it be ?

Answer 1

The impeller "sticks", most likely. Hangs upside down - "sticks off" and spins.
It is easy to treat: you need to disassemble the cooler, there is a latch in the center of the cooler under the sticker, remove the latch, remove the impeller and lubricate the cooler shaft.
If it is not clear, then the Internet is full of instructions "how to disassemble the cooler", google it.