Generator running two AC units, outlet appliances get hot

I have an Onan 5500 with about 240 hours on it right now which is supposed to run two rooftop AC units, but I can only get it to run the primary unit and not the bedroom. Both units work fine when I'm hooked up to a 30 amp circuit.

I also notice that when I have the generator on, anything I plug into an outlet (like a cell phone charger) gets pretty warm to actually hot, and that happens in a short period of time.

Any guidance on what I should be doing to correct the above is appreciated.