Chassis battery won’t charge from converter

Thanks guys, at this point I have checked for blown fuses, and with the help of a friend to push the button I believe I have determined the solenoid location to be under the dash in the area of the ac cool. As I said I know the converter is supposed to charge all of the batteries as it had no trouble doing so prior to late last season, so the coach sat unused from Nov. - Mar but still started on our first trip of last year without having to use the emerg. start switch. Now that I know what general area the solenoid is in I will do a little further diagnoses. Just so you are aware I am very well versed with the use of tools such as multi-meters as I am a master HVAC Tech. and an Extra class Amature radio operator. Thanks again for the ideas they are very good solutions if I can’t beat the gremlins.
Enjoy the journey. Tony/ KU4VA