Welcome PJTW TO IRV2.
Below in my signature are links to information to help you out and you can find other members down in the Newmar forum
to help you in follow up questions.
One thing with older coach's it is necessary to check wiring connections in your fuse panels and load centers because over time connections can become loose from road vibrations and heat differences.
Everything in your coach works off 12 volts from your batteries or the charging converter for your batteries.
The AC's, Micro, electric element for fridge and water heater will work when your plugged into shore power.
Here is a Owners Guide
for your coach and at the end off link you will see info related to your two electrical systems.
Use this and the QUICK TIPS LINKS below to help get you started any time you work on electric power have shore power disconnected and in your transfer switch there is still power in capacitors so be careful, would not want you to get hurt.