Rainmanrv, just for comparison, I can't hear my frig fan when inside the camper unless I put my ear directly on a solid surface that is attached to the frame. I can hear it if standing outside close to the frig vents.
I believe whether factory or add on, the frig may have a fan and it sounds from your question and statement that it's working pretty good. Is it in a slide.
What Old-Biscuit said is a fact of manufacturing. You sometimes see misguided manufacturing. Sounds like yours is o.k.
My TC frig application does not work without the fan and I'm positive of that.