RV Repair: Refrigerator problem switching from battery to electric, safety plug, heating element

Question
I have a similar problem to a couple of people here but it ends differently.  When my Norcold Fridge in my Thor 19" trailer switches over from battery to electric, it blows the safety plug breaker in the trailer at the sink and the breaker on the house outlet where it is less than 20 amps.  When the fridge is plugged in directly, it functions properly, ruling out the heating element as a problem and we replaced the wall safety outlet in the case of a ground problem there?  ANY IDEAS OF WHAT TO DO NEXT??  The A/C in the trailer and everything else is functioning fine.  HELP!!

Answer
Jeff, It sounds to me like possibly the G.F.I. that was replaced may have been wired up backwards. These are pretty easy to diagnose as they are predictable as to what they will and won't do. You may also want to check the body for voltage as maybe there is a grounding problem. Let me know what you find and we can go from there. Thanks, Bill