Welcome to the forum
Well the compressor is what makes it cold and the only "moving" part in the system, so only thing that could cause a rattle.
AC and refrigerators/freezers all work the same way
Compress a liquid and it heats up
Decompress a liquid and it cools down
Grab a spray can with compressed air inside and release some of that pressure, can starts to get cold, decompressing cools it down
So if your compressor is not increasing the pressure(compressing) like it once did then cooling wouldn't be like it once was.
Same if system is low on fluid, less fluid less compression so less cooling.