240 AC knob mystery

How does the AC control on the 240 (1989) fasten? Mine was converted to
Freon-less with the Volvo kit, which apparently replaced the dash
control, and the whole little rectangle is sort of loose now, even
though the knob/control is firmly fixed to the rectangle. There doesn't
seem to be a nut where I'd expect one, under the knob on a threaded
extension around the control shaft. I popped off the seat belt warning
light rectangle next to the AC position, but I can't see or feel
anything in back of the Ac control that's helpful. ?? thanks.

 

The conversion shouldn't have involved the control assembly, I suspect
it just became loose with age. Pull the knob off, now if you look
closely there's a seam around the panel and you can pop the rectangular
piece off with a tiny screwdriver revealing the nut you're looking for.

 

Just using up bandwidth to say thanks!