Older fridge cooling Better on 110 than propane

Cool a case of water in your home fridge, put it in the camper fridge. Wait a day, then check the temp.
If you are thinking a fridge is misbehaving a indoor outdoor thermometer with a thin wire to the remote sender and a memory is a good idea. Reset it every day, and you know what the high (and low) temp was.
Some people like the wireless kind, but I never got one to read thru wall of fridge. My brother uses one in TV to watch the temp of dorm fridge in TT, and another for the icebox...