Granvil, Are you certine you have only one engine driven alternator for all the batteries, chassis and house?

How many house batteries do you have and what size are they. What does the voltage on them read, engine off and engine running fast idle?

Do you have a drawing for the house electrical system?

Have you looked at every circuit breaker in the engine and electrical compartment and checked power on both sides (12 or 24 V)?