My first question is, is the AC on a 15 or 20 amp breaker. How long from the time you turn it on, first startup not after a trip, does it go before it trips? Does the AC breaker and the 30a trip at exactly the same time?
I would replace the AC breaker and see if it stops tripping.
Let’s think this through. If it is a weak breaker, (which is possible) then it should be the only one to trip. The 30 should not trip because the AC breaker tripped. Indicating something other than weak breaker
I’m not quite understanding the, one line from the ac was low. There are two conductors that are required for 120 volts to work. A hot, and a neutral. If I’m understanding correctly one of them has more amps than the other. If that is the case, then something in the wiring is not correct. The hot and neutral should be exactly the same amperage.
A possibility is that your rv is not connected to ground allowing the hot to touch the ground and then the neutral and ground would share the amperage of the hot. Do you have a surge protector that tells you that the pedestal power is correct?
Help me understand a few more things please.