: What would cause a refrigerator to make a knocking noise?
The knocking noise will be the refrigerant noise. ** This is a normal noise associated with the 134A refrigerant now being used.
Sometimes it can be muffled and maybe eliminated by adjusting the drier next to the compressor. Bending the drier in a 45 degree angle sometimes works but I strongly recommend having a technician do this because the line connected to the drier, can kink or break, if this is not done correctly.
Another possibility is, if there is enough cap tube (the very small line) that is attached to one side of the drier, it can be clamped to the discharge line. The discharge line is the hot line coming off of the compressor. Again, this is a job, I recommend having a technician perform. For more assistance, you can resubmit your question with more details.