Side vent refrigerators have problems with heat being removed from the condenser/absorber section of the cabinet as they usually rely on heat transfer via the heat rising and have no fan assisted induction of air. The hot air has to escape on a horizontal plane in stead of a vertical plane like a roof vent offers. Poor air flow results in poor heat removal. I had the same problem with a side vent Dometic in my camper slide out mounted refrigerator. After spending over $800 to replace the cooling unit a second time I added an ARP controller with fans. It should save my unit from overheating in the future but it also made a huge difference in efficiency. I can start the refrigerator at home now and it takes less than 2 hours to achieve 0-10 degrees F in the freezer section and 38-40 in the refrigerator. It has never been able to do that before. I don’t have big temperature swings anymore either. Although my Dometic has a small 12v fan below the condenser it never came on until ambient air temp was around 90F and by then the refrigerator section was near 55F and the temperature didn’t come back down until cooler night time conditions.
If you are having propane ignition problems you should also clean your flue and check the igniter gap.
Finally keep the refrigerator level. If off level the ARP will save it from overheating but it still needs to be level to operate correctly.