You are correct in as much as the "converter" has nothing to do with 120 volt power HOWEVER your 120 volt power center is usually i the same box with the converter. I would suspect a tripped breaker in the electrical control center (some RVs have one breaker that turns off the entire system. As mentioned earlier though, without 12 volt power anything operating from a thermostat would likely not operate. What SHOULD still operate is the Microwave and the outlets even without 12 volt power. If it's a combination of different things causing your problem like tripped circuit breaker and also tripped GFCI outlets (there are probably several circuits and each one would have to blow to make them all stop working OR one breaker in the electrical panel could do it.