Why is my Sub-Zero refrigerator not cooling?

What is actually going on

On these built-ins the refrigerator and the freezer each get a sealed system of their own, so a freezer that is still solid clears the expensive half of the machine before anyone drives out, and the whole diagnosis moves onto the refrigerator side. What is left there is a short list: the evaporator fan has stopped, the defrost heater has failed and the coil behind the rear panel has iced solid, or the thermistor that tells the control when to run that cycle has drifted out of range. All three are ordinary parts and most are a one-visit repair. If both compartments have climbed together, that is a larger conversation and it starts at the condenser.

What we check, and in what order

The condenser is where San Diego stops being one city. Behind the grille on a built-in sits a coil whose only job is handing heat off to the room. Within a mile or two of the water that coil lives in salt-laden air, and over several years the aluminum fins go chalky and lose the surface that made them work. Nobody notices, because the marine layer keeps the kitchen cool enough that the unit never has to try hard. Then a Santa Ana arrives, the house sits warm for three days, and a refrigerator that was fine on Monday is warm on Thursday. It did not break that week. It ran out of margin that week.

Inland the same coil is clean and the problem is the ask. A refrigerator in the inland valleys spends August rejecting heat into a kitchen far warmer than the coastal average, so a partly blocked grille, a slowing condenser fan or a gasket that has lost its pull shows up straight away instead of hiding for years. Owners describe it the same way every time: fine in the morning, warm by five, caught up again by breakfast. That pattern is airflow and heat load, and it is not a dying compressor.

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