Why has my ice maker stopped making ice?

The reasoning behind that

Undersized, hollow or half-formed cubes mean the mold never filled to its line, and that comes back to an overdue filter, weak pressure where the supply meets the inlet valve, or a fill tube with ice in it. A machine producing nothing whatever, in a freezer that is still perfectly cold, has a harvest problem instead: the module, its thermostat or its motor. Older Mission Hills kitchens add a third possibility, because the water line feeding a retrofit ice maker was run long after the house was plumbed, and it is often a long length of narrow tubing that never delivered full pressure to begin with.

How the diagnosis goes

We start on the water side because that is where the answer usually is. We measure pressure at the inlet valve, check the age of the filter, and look at the fill tube for ice. A machine fed by a marginal line will make small cubes indefinitely without anything actually failing, and fitting a new harvest module to that line produces exactly the same ice as before at considerably greater expense.

Scale is the local complication. San Diego water leaves mineral deposits, and they build up on the inlet valve screen, inside the fill tube and on the mold itself, where they slow the release of the cubes and make a healthy harvest cycle look faulty. An overdue filter compounds both. This is also why ice in these houses starts tasting flat before it stops appearing, and why we ask when the filter was last changed before we ask anything else.

If that matches what yours is doing, say so when you call — it decides which parts come on the van.