OP here -- no, I did not check the voltage with the A/C on -- I am not sure how one would do that? I measured the voltage in the outlet and the cords by inserting the two multimeter leads into the openings. When the A/C is on, the prongs of the plugs are occupying those openings -- no place to stick the leads!!
And although it does not seem likely that the A/C connections deteriorated overnight (they worked fine on Friday at an RV park), it certainly is possible. So my next move is to pull the converter out (with power unplugged!) and see if I can spot anything amiss in the breaker box area.
Assuming that I don't see any charred components, I will gently tug on the connections to the breaker for the A/C to see if something is loose.
If that does not pan out, I am at the limits of my ability. I do not have the skill to trace any possible intermittent fault in the circuit -- that is something I would have to take to the dealer or to a local repair shop.
Who knows? It is possible that this little glitch may have saved me from a big glitch (like a fire). If I learn anything of interest, I will of course report back.
