2013 Roo 183 and fridge is Dometic 2652rbx
I have the same only 2014...
With nothing in the fridge or only warm stuff it takes over 24 hours or more to start to get cool especially in any heat.
I always start with 8-10# bag of ice in the freezer section and let it work on electric before going anywhere... surprising that the freezer section is actually a pretty good ice chest, in so far as the bag of ice has never melted much even in the warm fridge...
As others have said, check the rectangular roof vent for insect nests... I also have a purpose made screen on the side vent to keep critters out. Remove the outside fridge panel by twisting the two black retainers 90 degrees. The panel should lift out.
I cut a piece of fiberglass screen and taped and glued it on the inside of the vent to keep out insects from the back of the fridge. Note on picture 3 wasps have built a couple of nests on the outside of the screen. I will clean those out before I put it back. Make sure the inside of the fridge controls is clean before putting the cover back on..