How do you know it was built into the panel when it was made? If you will notice, most everything else factory in that van has a label to tell you what it is and what it does, right down to silk screening on the cruise control stalk, if it was so equipped. That panel comes out separate from the heater controls, which are behind it and poke through a rectangular hole. If you take a Phillips screwdriver and remove the two screw that hold than panel in place, you will see what I mean. MoPar used the same heater control almost across the board in those years, and they are all accessed the same way.
You will also find a tiny LED like that one in most every automobile from that area with an aftermarket alarm system. The light in my '86 Aries K wagon is blue, and stuck in a different random part of the dash that is easily accessed for the installer.
Here is a typical MoPar HVAC control, with the fan switch removed, and a mounting ear broken off.
-John
