On most of the classics over 30 feet there is a power selector switch that allows you to choose to run the microwave, insty hot, nutone, AC, or refer. The choices changed from year to year. It was a compromise to allow for more than 30 amps worth of stuff to be run off a 30 amp power feed.
When the genset is running it powers everything. Both roof airs, as well. The selector switch does not come into play. This switch is normally in the overhead above the sink.
Another thing to check is to see if you have power to the outside outlets when on shore power and generator. The outside outlets are usually wired in series with the refer one.
WBCCI #5501 AIR # 49
1978 Argosy 28 foot Motorhome
Wise men talk because they have something to say; fools, because they have to say something. -- Plato