what is a flapswitch?

[flapsforty]

Mr(s) Yeager a most excellent explanation. Pictures help greatly for someone like me who has a vague idea about much of the mechanical stuff, instantly recognises the lay out of the various panels, but doesn't really know anything. Thank you for taking the time.

Follow up question, hoping you will indulge my curiosity.......

A flapswitch malfunctions. As per your explanation I now understand how this can cause ram air inlet doors to be not fully open (they can be fully closed as well right?) and thus no inflow of cold air into the heat exchangers. How does this cause a dual pack tripoff, and what is it please?