I have a Norcold 682IM that is 25 years old that works well until outside temps hit 90 plus and I see 40 to 45 degrees inside just like you are seeing. It will recover and go below 35 at night and cycle will start again. Temps are worst when ever we camp with family because the door is constantly being opened. So minimal door opening helps. Also I either pull in or back into a camp site so the sun is not hitting the refer. Another thing to consider if you are just measuring the air temp in side the refer and you see 40F the food will be colder. I put a glass of water inside and a thermometer inside the water and readings were much colder than the air temp readings and did not very as much with the opening of the door. If air temp was 40 water temp was 35.