Have you tried adding an on-off control? (The type I bought is usually used to turn lights on and off when you are away from home.)So you could plug the refrigerator in to that, and program the control to cycle it on and off. Get a small temperature sensor for inside the refrigerator, and you will be able to see how it does -- most give you a minimum and maximum history so you can, with some playing around, figure out how often to cycle it 'on' to keep it closer to the temperature you want. On my unit, I have managed to keep the interior within about 5 degrees (F) of where I want it.