I have a DMR 702 and it has an automatic fan that came from the factory in my Rockwood 8289Ws. Might want to check that there is no dead airspace above the fridge. Mine cools fine only the door latches are questionable at best. Door latch has been back to dealer 3 times and latch had been replaced once. Still doesn't work right. Guess engineers are always looking to change things even though the old style latches worked fine.
At this year's rally, a friend indicated that they had replaced the fans on their Dometic and had them out again to look at it. Apparently, the opening for the exhaust was too large, and the FR folks repaired the too large opening. We were having strange noises coming from ours and reviewed the fix for theirs, applied the same fix for ours and now the refer works better than it has for 3 years. Just a thought.