do you have the build sheet for your trailer? it will lsit the make / model / serial number that was installed? if you don't have contact forest river using their contact form and supply your vin and they can probably supplied the build sheet.
the converter may be many places. we have a different trailer but ours is hidden behind a bulkhead in the storage bay. look in your storage bay and see if there are any small access panels on the walls. if there are take the access panel off and see if the converter is back behind the wall. of course different models could put them different places.
2015 cardinal model 3825fl
2015 dodge ram 3500 dually