Why is my Sub-Zero refrigerator not cooling?

Why we start there

If the freezer is still hard, its own circuit is healthy and the search moves to the refrigerator side: evaporator fan, defrost, damper, or a condenser too loaded to shed heat into a Temecula afternoon.

What happens next

Sub-Zero calls the architecture dual refrigeration, and it is worth being precise about what a cold freezer actually proves. It proves that one complete circuit is well — that compressor, that evaporator, that airflow and the power feeding all of it — and it moves the search onto the other circuit. On the refrigerator side, airflow, defrost, a damper and the condenser all sit ahead of that circuit's own compressor on the list, and they account for the overwhelming majority of these calls. The word we hear most on them is intermittent, and it is almost always the wrong word. A refrigeration system has only so much capacity in hand, and every degree the kitchen gains through a valley afternoon spends a little more of it. A coil carrying a year of dust still has enough in hand at seven in the morning and has spent the lot by five in the afternoon. Then the breeze comes through from the west, the house drops, and the system takes the number back overnight. One appliance, one fault, and two entirely unlike sets of numbers depending on the hour a technician happens to be standing in front of it. If you can tell us the time of day the trouble shows up, do. It is worth more than any other detail you can give us.

The order matters more than the list does. Airflow and the condenser come first, because that is the fault which imitates every other one. Then evaporator fan current draw on the refrigerator side. Then the defrost heater and the thermistor, since ice on the coil chokes air long before it chokes anything else. Then the defrost circuit on the refrigerator side, then the gasket, measured for pull rather than looked at. The sealed system is the last thing examined, not the first. On a unit whose freezer is still cold it is almost never the answer, and it is comfortably the most expensive thing in this trade to be wrong about.

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