A little FYI if you have this problem. We have been living in our 5th wheel for the last 5 months and our refrig. started to slowly warm up. First noticed things in freezer not freezing and just didn't seem cool in refrig.. Moved everything to new refrig. in house and started troubleshooting our 5th wheel frig.. First checked that air flow was not obstructed - OK - then also looked for Codes on front of refrig. - no codes. AC good to frig., DC good at frig., no difference running on propane. Checked wattage on AC heaters (my unit has 2) - both OK (mine are 225W each). To check this you need a clamp-on ammeter and voltmeter. Volts (AC) at plug for frig. times amp reading will give you watts. Again, all good. My unit has a thermistor (its like a thermostat on older units), so unplugged it in the refrig. and turned unit back on. Checked the next morning and refrig. was down to below zero. Bad thermistor - ordered one for my unit from Amazon (Prime) $17 and two days later we have frig. back to normal.
Hope this will help and one that has refrig. trouble. Happy camping
PND
Now retired
2012 Mountaineer