A quote from "Everything About RV'ing"
The simple answer to your question is no, you do not have to leave your RV's fridge running to extend its lifespan. RV Refrigerators are designed specifically for RVs with the understanding that they are turned off and on frequently.
The only thing that you will do by leaving the fridge on is increase your energy usage. A good rule of thumb is to turn on your RV Refrigerator 24 hours prior to going camping. This gives the Refrigerator time to cool down sufficiently.
Jim in Memphis
Wife of 45 years is Brenda
Recently sold our 1997 24' Classic
2014 Ford F-350 6.7 Diesel Crew Cab