house 12 volt sytem out

I have a 96 Winnie Vectra 36WA and am in the process of preparing it for the season. The house batteries are fine as they will start the truck when truck battery is bypassed. The 12 volt sysrwm works fine when plugged into a shoreline. Will not work at all when no shoreline and batteries are only source. Checked all breakers but who can really tell with those dumb little round things.
Manual says that converter is in compartment forward of right rear wheels. Of course it isn't; and I can't find it anywhere else.
Have had this rig for years and no trouuble at all. Never needed to troubleshoot.
Can anyone come up with any helpful suggestions before I have put a smile on the face of an RV technician?
house 12 volt sytem out

Locate the cable feeding your house fuse/circuit breaker panel. Check the voltage there. If the system was working when you parked it and the coach batteries will start the rig, I am guessing you just have a dirty connection somewhere. When you are plugged into shore power put your ear to different points around the coach and see if you can hear the hum. I guessing you can find it that way and check your connections there.
house 12 volt sytem out

My converter/inverter is located under the fridge.
I would look for a "Air Return Vent" like the one for the furnace..

Because an inverter/converter heats up when in operation, it will need an "airy" space to dissipate the heat.. thus the register vent..

If you don't have a register vent other than the one for the furnace, then likely the converter/inverter is located with an outside vented access, like in the basement area..

just a thought,
house 12 volt sytem out

I hang my head. I never knew that there was a SWITCH UNDER THE DASH rhat turns the house system on or off. Everything is working fine. I thsnk you all for your efforts.