Question about the volcano hybrid

[RST1124]

I notice that sometimes, while the unit is heating up, it will activate the fan and blow air for about a second. So if I’m preheating some material in the filling chamber on top of the volcano, it will sometimes eject smoke prematurely, as if I had pressed the button to turn on the fan.

Is this normal?

 

[DrJynx86]

The manual says it will turn on briefly the pump to audibly signal temperature has reached the selected value. Page 23:

The heating process is completed when the set value is equal to the actual value. This is also indicated acoustically by briefly switching on the pump (can be switched off using the app).

Why don't they use a buzzer to do acoustic signalling on such a high end piece of tech is out of my comprehension.