In our 22 cu ft GE SxS fridge /freezer, the freezer fan speeds up and slows down frequently and creates a whoooing sound like a quiet hoot owl when reaching the peak speed of the speed up phase of the ebb and flow of fan speeds. Fridge/freezer works ok, it is just this unusual sound pattern that puzzles me. i know that the new models do have variable fan sppe but is this normal?

I have had some of these units making noises like this. One I found was leaking water down from the water inlet tube and in behind the ice maker and behind another panel that shoots up to the ice maker and building up behind that panel and causing a whistling sound. Removing the ice build up solved this one problem but couldn't find solution to the problem for the other. Dismissed it to change in the weather and expanding and contracting of the liner of the unit. Hope this helps.