Battery not charging (from chassis or generator)

Yes, the lights work. The water pump works. The AC works. All while the generator is on. When the generator is not on the lights and water pump work.

Where would I look for the converter? How would I check if it is functioning correctly?

Even if the converter is bad, shouldn't the chassis alternator work to charge the house batteries? It seems unlikely that both the generator converter AND the battery isolator would both be bad, right? Where would I find the isolator and how can I test it?

Thanks!