I think it is coming from the compressor. It just stopped one minute ago.
Presently everything is still frozen and cold.
Thanks for your help.
The put put put sound has started again and is coming from the bottom of the refrigerator and freezer. It seems a bit louder in the refrigerator. I think it may be the fan.
Thanks for helping.
This is Peter, Susan's husband. I have pulled the panel off the back of the refrigerator and am examining the guts of this thing. It is clear that the thumping sound is coming from the round structure, part 725, on your diagram. I can modify and turn the sound off and on by giggling the part. Is that the compressor?