Sub zero coil makes clickity sounds when compressor is runnin
I have an older sub zero model 511 if I recall that has recently started making odd sounds. The coil is located in the back of the refridgerator wall, and has begun to make random loud clicking sounds when the compressor is running. It sounds almost like ice crackling even though there is no ice. Also the sound seems to come from the upper right quadrant of the back wall. There are no fans or moving parts in the vicinity. The sound immediately ceases when the compressor shuts off.
Anyone have an idea as to what this could be?