Why does my ice maker make a knocking noise?

Some knocking and clunking from an ice maker is completely normal, as ice drops into the bin, the machine cycles through making and releasing ice, and the pump and compressor run. A countertop ice maker in particular makes a fair bit of noise for its size. But a loud, new, or unusual knocking can point to something laboring: the water pump struggling, the compressor making noise, the ice ejection mechanism catching, or simply the machine sitting unlevel on the counter so parts knock as they move. Most causes are easy to check. The countertop models in our best countertop ice makers guide are not silent, so the key is telling normal operating noise from a sign of trouble.

The normal noises

An ice maker has several moving parts and a refrigeration system, so it is never silent. As it works you will hear the compressor hum, the water pump circulate water over the freezing element, and, most noticeably, batches of ice dropping into the bin with a clatter or knock as each cycle finishes. The machine also makes sounds as it starts and stops cycles. This regular rhythm of humming, pumping, and ice clattering into the bin is the sound of the machine doing its job, and on a countertop model it can be surprisingly loud for the size. If the knocking is the ice falling and the machine is making ice normally, it is nothing to worry about.

An unlevel or loose machine

A common cause of extra knocking is the machine not sitting level or steady. If the ice maker is on an uneven surface, or not sitting flat, its moving parts and the water sloshing can cause it to knock or rattle against the counter more than it should, and vibration can make it tap against nearby objects. Make sure it is on a flat, stable, level surface with a little space around it, and that nothing is leaning against it. Also check that the ice scoop or any loose part is not left inside the bin where the moving ice or paddle can knock it. These simple placement fixes cure a lot of unnecessary noise.

The water pump

The water pump, which circulates water from the reservoir over the freezing element, can become noisy. If the water level is low, the pump can draw air and make a knocking or gurgling sound, so check the reservoir is filled to the proper level. A pump clogged with scale or debris can also labor and knock, which is one more reason to descale and clean the machine regularly. If the knocking coincides with the water circulating stage of the cycle and the reservoir is full and clean, but the noise persists, the pump itself may be wearing, but low water and scale are the usual, easily fixed culprits.

The ice ejection mechanism

The part that releases the formed ice into the bin can also knock if something interferes with it. If ice has clumped together, jammed, or built up because the bin is full and the sensor is not stopping it, the mechanism can labor and knock as it tries to push ice out. Clearing any jammed or clumped ice, making sure the bin is not overfull, and checking the ejection parts move freely usually resolves this. A buildup of scale can also stiffen moving parts. So if the knocking happens at the point the machine ejects ice, look for a jam or clumping rather than assuming a serious fault.

The compressor and when to worry

The compressor, the heart of the refrigeration, hums and can make some noise, and a change in its sound, especially a loud knocking or rattling, can indicate it is laboring or a mounting has come loose, though this is less common. If, after checking that the machine is level and stable, the reservoir is full, the machine is clean and descaled, and no ice is jammed, a loud knocking still persists, it may point to a failing pump or compressor that needs service. Given the cost of countertop machines, a serious compressor fault often means replacement, but the simple checks resolve the great majority of knocking noises first.

The short answer

So a knocking noise from an ice maker is often normal, the sound of ice dropping into the bin and the pump and compressor cycling, and countertop machines are not quiet. A loud or new knocking usually has a simple cause: the machine sitting unlevel or loose, a low reservoir making the pump knock, scale or debris, or jammed and clumped ice straining the ejection mechanism. Level and steady the machine, fill and clean the reservoir, and clear any jammed ice, and most knocking stops. Only if the noise persists after those checks is a failing pump or compressor likely, which may warrant service or replacement.