It sounds like the circulating fan for sure, your cpmpressor is plumbed into the freezer, the evaporater sits behind the plastic wall in the back, this keeps the freezer ice and cold. From there a small fan blows cold air off the evaperater thru a snall ductwork into the fridge. Thermostat would be in fridge section so the compressor will keep going until the fridge gets to X. If the fan quits the freezer will get colder than ever before but the fridge will actualy get hot from the heat of the compressor running under it. Very slowly remove the screws in the freezer section after alowing it to warm up to room temp don't try to do it cold the plasic will be very brittle. You wil have to pull various section of the interior plastic to get off te back section basicly a jig saw puzzle. When it is apart you will see the fan. Take a little carb clean and spray around the shaft of the fan while turning the blade by hand, after a bit it will free up, let it sit for 10 to 15 minutes and get the smell of the carb clean out plug it in and th fan should start spinning again, now spray a little WD-40 on the shaft while it is running and put your cabinet back together. I have done this on 20 to 30 units over the years and have yet to find a burnt out motor they just cum up. Be carefull with the carb clean it will remove the resson on the shaft which is binding the motor but it is flamable give it a chance to airout before starting it up again. Also beware of overspray using it, some plastic panels may not like it.
Good Luck,
Tracy