Buy a multimeter, then you don't have to remove the breaker. Just check for voltages along the way and at the AC unit itself.
Using a multimeter
https://www.rvtravel.com/rv-electric...-meter-basics/
Basic uses of a multimeter for RVers
Be aware the 120vac power goes from the breaker to a "Power Sharing Switch" behind the basement wall on the ceiling under the stairs. This Switch is for the 3rd AC unit to share the circuit breaker with the bedroom AC BUT only allows the 3rd unit to run IF both are turned on at the same time.