May I suggest going to Coachman’s website and get all the manuals for your coach. They likely won’t tell you where the relays are, but they will probably give you an idea of the circuitry - and from that you can possibly track down where they are.
Possible locations - under the refrigerator, under the kitchen or bath sink cabinets, in the electrical bay. Chances are, yours isn’t just a relay but a circuit board with 1 or 2 black cased relays in the board(s).
91 Ultrastar Champion02 Georgie Boy Landau 8.1l Workhorse
03 Jeep Wrangler TJ 2018 Jeep Wrangler JK toad