First ascertain exactly where the noise is coming from.
1. Inner fan? - With inner fan there are a few ways it can become noisy;
   a) Fan is faulty, and bearing has failed, this will make a very loud noise, new fan required
   b) The unit has iced up on evaporator, causing fan to hit ice, this will eventually strangle fan and it will fail
   c) Something may have come loose near fan, like screws that hold it in or a wire has made its way to get touched by blade

2. Rear fan?
   a) Fan is faulty, and bearing has failed, this will make a very loud noise, new fan required
   b) Something may have come loose near fan, like screws that hold it in or a wire has made its way to get touched by blade

3. Compressor? - This is the main working motor of unit and starts and stops 6-8 times an hour. If uneven this could make a noise during running. Check the bolts that hold it in place havn't come loose.

4. Foreign Rattle - With fridges the actual piping has liquid and gas running through it 100% of the time, this can cause piping to vibrate during operation, if the piping is close to another part of the fridge it could make a sound if it touches another part.

*Note: If a fan has stopped working it could be that the transformer that actually runs the 12V fan has failed, so that needs to be diagnosed. 

Parts
Inner Fan, part number YC150D-FAN-INNER-TOP, $69.00, complete below to start process
Inner Fan, part number YC150D-FAN-INNER-BOTTOM, $69.00, complete below to start process
Inner Fan, part number YC150D-FAN-MIDDLE, $69.00, complete below to start process
Inner Fan, part number YC150D-FAN-UNDER, $69.00, complete below to start process
Transformer, part number YC150D-TRANSFORMER, $49.00, complete below to start process