Most everything save the microwave and the opitonal RESIDENTIAL Fridge use 12 volt DC, this includes the water heater, and Air Conditioners. But the WASHING MACHINE. I would think woudl be a 120 volt only device.
Suspect list as follows. with comments
Circuit breakers: These are always #1 Includes the MAIN breakers Cycle them.. Most people think if one trips the other does too.. not true.
GFCI is #2
Joke (not)Many RVers have a few screws loose.. Story:
When this righ was like six nmonths old the Air Conditioners were giveing me fitsk Sometimes the front one would work, sometimes the rear, sometimes both or neither,, So I started trouble shooting.. By chance I started with the breakers.
Noticed some movement in one of the wires where it is clamped to the breaker.. Yup, screw was loose. One screw took over TWO FULL TURNS before I felt resistance and over 3 full turns to tight.. Several were loose.. White, Black and Green, all 3 colors.. So the lose screws are the kind you tighten with a #2 square bit.
Side note: Another RVer citing my joke found some loose nuts on his 12 volt side of life. So we have loose screws and loose nuts.
As others have said LIGHTS are a 12 volt item, as is the furnace.. You said Batteries are CHARGED.. how are you measuring.. At battery leads one to think the DISCONNECT may be in the DISCONNECT (Store of OFF position) I had that problem too once.. Converter should supply 12 volt power if that happens and you have shore power but if there is a tripped breaker........
Finally.. You said MICROWAVE (And I assume televisions) work.. IF YOU HAVE AN INVERTER... That may be powering TV and Microwave. (off batteries) It will nto be wired in via the disconnect but will go direct to the battery via a fuse.
True Story (And this too is a suggestion) Had a neighbor with electrical trouble. In his case the Televisions did not work (KEY CLUE) Well he opened the compartment where his inverter resides, and there it was. a tripped breaker.. He then went inside to check if the TV worked (it did) his wife asks if I thought I could help, he tells her "he's already fixed it".. I come off looking like a super star. And it's all the fault of forums like thies cause my inverter does not have breakers, it feeds a sub panel (breaker box) so I'd not have thougt to look at the inverter without you folks.. Thank you.