Mine comes on under the load of just a few lights and the converter itself, of course. It's nearly silent, and I wouldn't have known it came on if I didn't have the cover off for something else.
I would guess your fan is getting ready to expire, and the bearings are starting to sound off.
Ford F250, Crew, 6.2 Gas, 4X4, Short Bed, Companion Hitch
2019 Jayco 28.5 RSTS, MorRyde orbital