Under unit is a small fan that sometimes can make a noise if the 'bracket'' holding it comes loose, it creates a vibration. Sometimes a wire may have come loose and is now hitting teh blade as it rotates. Both are easy to rectify without the need for a technician. Of course turn unit off before you check in there, you access by removing front bottom cover.

This fan could also be faulty when a bearing goes, replacing fan the code is SK135-FAN-UNDER, price is $89.00, contact below to arrange

The compressor is the main working part, and this will make a start up and shutdown noise, this is normal. If during running you have a 'rattle' then try tilting fridge a little to left right back forth etc. It could be that the compressor is not level, as that couses a rattle. If compresser is constantly clunking it may be faulty, replacing is part number SK135-COMPRESSOR, price is $239, contact below to arrange

Parts
Under fan, part number is SK135-FAN-UNDER, price is $89.00, contact below to arrange.
Compressor, part number SK135-COMPRESSOR, price is $239, contact below to arrange.