Well there are a lot of variables that go into saying if it is right or not.
1- How cold were/are the items in there, already cold or warm?
2- How much is in the fridge (an empty fridge has more of a problem staying cool)?
3- How often is the fridge open and closed?
4 - What type of venting? A roof vent tends to cool better in still air. If no roof vent then you may want a fan.
5 - How old is the cooling unit?
6 - Does the fridge cool better in the same heat on 12V or 110? Could be the flame is low and needs cleaning.