I'd ask the selling dealer about the cooling problem. It costs nothing, and you might just get lucky.
If you have a thermister on the cooling fins it may be moved small increments (1/2") at a time. Allow 24 hrs. to see the results of each move. Move it up for colder, if it gets a little colder but not enough, move it to the next left fin, starting at the bottom of it. Some models/makes have the thermister adjustment on the back of the frig., see owner/service/installation manual for that:
Aero-Rv.com - Aerolite Ultra Lite RV Travel Trailer and Expandable Hybrid Campers . Click "appliances", then select your make/model to download the pdf.