This sounds to me like the heating element, just like mine! Fridge works fine on Gas, but on electric, NOTHING. Unplug the fridge, and find the heating element inserted into the Flue. there are 2 thick wires coming from it. Take a multimeter and measure the ohms of resistance across the 2 terminals. If its ZERO (like mine) its shot. Now if you are getting a reading on it, you need to make sure that the ohms of resistance is equal to what the manufacturer calls for. (Find this on the internet)... Mine should have been 44 ohms of resistance. If its below specs, the fridge will never cool correctly. it may be slight.
Do a web search on Ford RV refrigeration and find his video on you tube. He walks you through the process of testing your fridge. He is a great guy and will even offer advice.
