Might also have a nearly broken wire connection within the adapter.
Is this 50/30 adapter further stepped down to a 15A household-type plug? If so, running the a/c for long hours, in addition tot the usual background loads, has probably pushed the adapter beyond its limits. Most people don't realize that a 15A plug is actually rated for only 80% of that in continuous use, so its 12 amps continuous and 15 amps for only short periods. Your a/c and battery charger together draw about 12A-13A continuous.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL