Seems like you need to be checking the 12VDC sources. The first thing to check us the 12V coming from your batteries. That power goes through a circuit breaker, normally 40 or 50 amps. The breaker is near the battery, probably mounted on the wall, looks like a terminal block, usually has large red cables going in and out. There is a small button on top or on one side that is the reset. This would be the first thing to find. The A/C is probably not workjng because it requires 12VDC for its control circuit, so finding the 12V should solve that too.
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