Refrigerator warms up when driving

The NDA 1402 has 2 drain tubes for the evap fins. In the bottom back wall of the freezer side is a drain hole. Below the refer side evap fins is a drain pan and that also has a drain tube that goes out the back of the refer. They both combine to a T fitting with one drain hose. So, odds are from 8 years old refer, that white plastic drain line has deteriorated and you basically have a hot air egress into both sides of the refer. When in transit, these open hole/s will be sucking in hot air. Check those drain hoses. Also, if the hoses are in good shape(I doubt it), plug them off and then do your next test drive. This is the most common cause of temp rise in a Dometic refer while in transit. Doug