Yep, that's the end of that cooling unit. The yellow color is from chromemate which is in the solution along with ammonia inside the refrigerator. The boiler has failed. Perhaps from constant overheating from operation with the RV out of level. The thermal sensor tripped because the heater was heating the boiler but that heat wasn't being carried away as would happen if it was working normally.
The cooling unit can be replaced without replacing the whole refrigerator but the difference in cost isn't all that great and you'll only save money if you do it yourself because of the extra labor of taking the refrigerator apart and putting it back together again as opposed to pulling the old refrigerator out putting an new one back in.
