Which Dometic model do you have?
IS your fridge a 3 way.......runs on 110V AC (heat element), on propane or 12V DC (heat element)?
Unusual for 2013 new larger fridge to be a 3 way??
On DC....what do you mean? DC heater element or DC and using propane?
12V DC is used on electric and propane modes....control circuit/gas valve/spark control
DC heater element....that 'mode' is mainly for when traveling and to just maintain a cold fridge vs getting one cold.
The DC heater element is a low wattage one due to being 12V DC. So it's heat output is much less.
Have you checked IF element is bad?
So what DC mode is causing problems......propane heating or DC heater element?