How to isolate a refrigerator?

Moving the A/C unit could solve the problem but the longer the lines the less efficient the A/C is. But a small trade off for the solution you seek. If you do have it mived have a extra thick concrete platform poured. That will help in vibration. One thing to answer your question is, yes the a/c unit needs to be level, and isolating the tranfer lines from the wall pass thru will help too.

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Ebm,
R u serious?

The distance between A/C units in a split system will not affect the efficiency of the unit unless the length is over 100 feet. Copper line sizes are compensated for distance. Split A/C systems are designed and factory charged for up to 50' of copper lines between units. When the copper line sizes are increased for a run over a 50' Freon would need to be added. If the line size was not increased for a distance over 50' then efficiency would suffer.

Ductless splits are the exception, 35 feet max, anything over that distance would affect efficiency.

The food will sound better just an idea.Maybe to costly does work great on amp,cd player etc.