AC light off when AC is on

I thought that my AC was broken. I finally figured out the problem: my AC light on the rightmost button on the control panel is off when the AC is on, sometimes. So this time the AC was really off, so all I had to do was press it, the light came on and the AC was working again!

So how can I get the AC light to go off when the AC is on? Easy: by pressing twice on the Auto button!

Is this a bug or a feature? Could anybody in this forum try this and see it does the same or if it is just a problem with my car?

Thanks in advance!