Your coach probably still has the original Univolt converter. I would start at the battery location, look and listen for something humming. The converter is typically located near the battery and the AC power panel may be in the same area. The humming will only be there if you are plugged into shore power and the converter is powered.
Not being familiar with the layout. I can only give you clues. In my '74 Argosy, the converter and AC panel were located in the street side rear closet. Way back in the corner. A real bitch to get to.
The converter may have the 12 volt
fuse panel built into the end. Look for a cover with a knob that hinges down.
Does the coach have a compartment in the back below the window or a small compartment forward of the rear bumper. Either way, look in there, it may give you a clue on where the wiring goes.