A constant loud rattling noise throughout most of the day and night from a KGN33V60 model, appearing to come from the freezer compartment, for a very long time. This is the third replacement model we have had now. Two engineers said they could see no fault with this one after close examination, after the previous two packed up and didn't work at all. This model had been recalled according to one and had not to another. Who to believe? I have what sounds like a similar problem with a Bosch Bottom Freezer KGN39X00GB. I have defrosted it and within a day it is making the noise again. I think that the fan in the freezer section gets iced up then cannot turn, which causes the noise?

Lots of stuff can cause noise. The only moving part in the freezer is the fan. I don't know of anything else that moves. If ice build up is an issue, then there are several things to concider.

Not enough defrost time. Cycle too short or heaters are not hot enough for some reason. Could be undersized heaters from manufacturer.(?) Defrost timer could be bad causing short or no defrost at all. This timer also controls the defrost heaters and compressor being off during defrost.

Be sure the seal around the door is tight. No air gaps. Warm air (contains moisture) will cause freeze ups. Long shot is that the thermostat is bad and unit never shut off. If timer is bad, compressor coudl be running during defrost cycle.

Hope this helps