From what little I can tell by Googling Ever Chill, it is a low cost, probably Chinese made 12V refrigerator. It probably doesn't use the ubiquitous Danfoss compressor (or if it does, it is a knockoff) that most quality DC fridges use.
For all I know there is a separate compressor for the freezer vs refrigerator compartment and the freezer compressor is not running for some reason. Here is the link to their instruction manual which doesn't give an info on your problem in the troubleshooting section:
https://clearvision.canto.com/pdfvie...f5t&suffix=pdf
Due to the lack of data on the manufacturer's web site, I doubt that you will get much support. But contact them here and see what they say:
https://www.wayinterglobal.com/pages/contact-us
Oh and plugging your RV into a 15A, AC 110V outlet just lets its converter keep your batteries charged while running off of DC. It should run fine with no AC power, at least for a while off of the batteries.
David