My Adler 12v cold plate system works great in very hot weather. I built my own 7cf box type ref. and used 3 inch insulation around the entire box and have never had a problem even when in Costa Rica. I did the same with my 5 cf freezer. Everything stays nice and cold even with temps in the 90"s inside. You can purchase hitech insulation in 4x8 sheets to insulate your refer. Very expensive ( around 350.00 per sheet) but very efective.