Take the inside panel off and look at the condition of the wood from the inside. Only one seal on the a unit that seals it and that is a 14x14 foam seal and the bolts that hold the unit down need to be checked every year for proper tightness to ensure the seal is tight. I bet they are loose and just enough water is getting in then being wicked away by the roof to not drip on the inside but cause damage that shows up 6 years later. Good luck and hopefully insurance will take care of it. Have your son try and remember if any low branches going to and from a campground that he might have had one contact the ac unit shifting it causing it to leak. Therefore a legit claim. If no damage from that then unfortunately it will be out of pocket.
07 jayco 314 bhds