Rick, an awful lot depends on the ambient outside temperature, and if you are in the heat belt that's taking in much of the country this week, you cannot expect the fridge side to keep up. It's just too hard for it to exchange internal heat to the outside. That's especially true if even overnight outside temps are quite high, so that the unit hasn't even got any catch-up time.
It can be helpful if you can park during the hottest part of the day with the fridge side in tree shade, and open the outside access door especially at night. If your unit doesn't have one or more small fans top and/or bottom back there, consider adding them; it made a nice performance difference in our 1985 coach when I installed a fan with switchable solar or 12v power, so I could run it in shade or at night. If your fridge does have factory fan(s) to move air over its rear tubes, be sure they are functional.
That said, if the thing was acting up even in moderate ambient temperatures, you should be aware, if you aren't already, of a significant Norcold recall spanning many years back. Even recalled units have reported problems, so check into that; many members here have experienced the situation, and reading their woes made me count my blessings we have always had Dometic.
When we began motorhoming, I went through 2 cooling units on our "85 Pace Arrow's Dometic. Dometic made pretty good units (modern ones are even better, and less level-sensitive), and the fault both times was mine. Dometic fixed the first one under warranty, even though chances are it was my negligence (or ignorance at the time). The second time was just stupidity, leaving the coach off-level on a boat ramp while I crawled underneath for 2 hours trying to figure out why the coach wouldn't start. I knew better and should've turned the fridge off like I usually do when parked off-level; I just didn't think about it while possessed in summer heat on asphalt trying to find what was wrong with the ignition or starter.
The really dumb part - wait for it ...
I'd left the tranny in Drive, which is why it wouldn't crank. An $800 reason to always bring your brains to the party!
Our current 2-door Dometic has been pretty much trouble-free, and I wouldn't convert it to residential; the exception there might be the fact they quit making our specific model in 2008, so if it quits altogether, residential might be an option in lieu of a new cooling unit. But with no spare room in the battery bay for 2 more 6v., and our penchant for dry-camping at Camp Sherman and other Forest Service campgrounds, I doubt it.
It's just a great fridge, performing well for 10 years, even in weeks of scorching eastern Nebraska heat and humidity in 2012, thank goodness - cold pop, door-delivered ice, water, and beer was always at the ready.
-Joel
