Sometimes the relay will be located under the passenger side seat, which is relatively close to the coach batteries, if they're located under the side entry steps. The 2007 Navion Operator Manual calls it the "Battery Boost Switch". I don't know what the parts manual calls it.
Is the fridge a Dometic 3-way? (AC, DC, LPG)? Odds are it's fine, and you can test it any way you want. Just keep an eye on it, in case there is a problem.
I had a 3-way in my Roadtrek and we were rarely 2 degrees from level, and it ran like that for years. I think they're pretty forgiving for that, like the Shurflo water pumps are for running dry for hours. They're bulletproof, too.
