How about your fridge? Is it working correctly on battery power? i"m wondering if you don't have the battery leads connected with reversse polarity. It SHOULD be negative ground and negative wire is the white wire. If you hook it up backward LOTS of things don't care (lights, fans, slide room, heating devices) but other items require correct grounding. There are two fuses that are DESIGNED to blow if hooked up backward to protect these items. Just something to check and the GOOD news is that is it's backwards, nothing will be harmed once the fuses are installed AND grounding is corrected.
Good luck / Skip