When I have faced low Voltage coming into the RV from the 30 AMP connection at the Parks post, the whole RV 110 Volt electrical system shut down. The times it has happened I could run the "Fan Only" by moving the fan selector off of "Auto" to the "ON" side of the A/C but when I turned on the compressor or in other words moved the switch to "COOL", the system would drop out.
I'm guessing here... but I think it's a low Voltage protection built into the RV Converter. In those times I had that problem, after the low Voltage was corrected (By either moving to a better site or by the electrician dealing with their 110 Volt Connections) my Converter reset and allowed power to flow.
Be sure to check the GFI in the bathroom. That circuit seems to be connected to several other outlets, often the Fridge is also on that electrical line. Even though the breaker is On, if the GFI has tripped out... it as well as anything connected to that circuit will be off line.
Hope this is some help.
Marv