Thor Hurricane 29M (2016), has a clicking sound from underneath the refrigerator. It is not the same clicking when switching from electric to propane. It even has a slight "boing" sound.
I don't know your coach layout but what is physically located under your fridge (I assume you are talking inside the coach)? If there is a drawer or removable panel/vent have a look and see what is in that space. (hopefully no happy rats - kidding).....you might have some other electrical devices not even related to the fridge hidden under it.
I did a quick search on 29M 2016 Hurricane and if the correct coach is shown it looks like you have the furnace below the fridge vent on the outside. So the clicking might be something going on in the furnace? When do you actually hear the clicking noises......maybe when there is a call for heat?