Atten 8586 Solder Iron scratching clicking noise

[Shadow85]

Hi all

I got the mentioned 2-in-1 rework station which is sold under different names to start learning hot air soldering.
Strange thing is that if if use the solder iron, there is a strange noise which sounds like an old hard drive. Scratching/clicking.

I'm wondering where it could came from. Its only when it already has reached the given temperature and just trying to hold it, you see a blinking dot in the down right corner of the display.
If it heats up or cools down, i hear nothing.

Of cause, i can send it back, but i'm interested what can produce such a sound.
Thx for reading.

[wblock]

Does the clicking correspond with the "heater on" dot in the display?  Then it's probably an audio effect from an inductor or other component.  A relay would do that, too, but finding one controlling the heater in a modern soldering iron would be a surprise.

[Shadow85]

Does the clicking correspond with the "heater on" dot in the display?

yes. But only when the dot is flickering. During heat up where the dot stays on, there is nothing.

[Rasz]

arcing?
quality of those units is pretty shit