Absorption units don't make very much noise when running. In fact on electric, they don't make any noise at all. Especially if they don't have fans in the vent stack.
On gas all you may hear is the burner flame, and it's so small that you can barely hear it.
We had our fridge off this past Friday when leaving for a trip, so I turned it on when we left and the freezer was freezing when we got to the campsite about an hour later, but the fridge part took about another 3 hours to get to fridge temps.
Keep an eye on it and let us know if you have any more problems.
Salem 29RKSS Pushing a 2500 Mega-Cab CTD!
Gotta go campin!