Ice maker problems, cause by cause

Not enough water

This is the biggest group by a distance, and it produces hollow cubes, undersized cubes, and short batches. The chain has four links: the supply pressure at the property, the isolating valve, the filter, and the inlet valve on the appliance itself. Scale attacks the last of those, and a valve seat with scale on it neither opens fully nor closes fully — so the same fault can give you small cubes and a slow drip at the same time.

Safe to check: that the isolating valve is fully open, that the filter is not long past its interval, and whether other fixtures in the house have lost pressure too.

The harvest is not completing

If the mould or the plate has water in it and nothing is being ejected, the freezing side is working and the release side is not. On a built-in ice maker that points at the mould heater, the ejector or the control; on a standalone clear-ice machine it points at the harvest valve, the cutter grid or the sensor that decides a slab is ready. Neither is a user-serviceable item, but knowing it is a harvest fault rather than a cooling fault saves you being told the machine is finished.

The drain

A leak tracking down the side of the cabinet is a drain problem far more often than a supply problem. Blocked line, failed pump, or a drain that was routed upward at installation and has been marginal ever since. Water pooling under a refrigerator, by contrast, is usually the defrost drain rather than the ice maker at all.

• Hollow, shelled or undersized cubes: water volume
• Water in the mould, no cubes: harvest
• Slab of fused cubes: batch held too long, or a bin nobody empties
• Leak down the cabinet side: drain
• Stale smell after cleaning the bin: biofilm in the water path

When it is worth a visit

If the supply checks come back clean and the machine still misbehaves, the remaining candidates all sit behind a panel. A visit measures supply pressure at the cabinet, runs the harvest cycle end to end, and checks the drain and pump — and the flat $95 for that diagnosis comes off the repair if you approve one.