Around Todos Santos and the older streets of Concord there are plenty of kitchens with a fifteen- or twenty-year-old built-in Sub-Zero still doing its job. So the question we hear most is not "what's wrong" but "is it worth fixing, or should I replace the whole thing?"
The honest answer almost never comes from the age or the brand alone. It comes from three things: which part actually failed, whether that part is still available, and what the sealed system reads on the gauges. Here is the same framework we use on a Concord service call.
Usually worth repairing
A failed evaporator fan, a tired door gasket, a clogged condenser, a control board, a water-inlet valve or an ice-maker module — these are bounded, well-stocked repairs on a unit that is otherwise sound. Sub-Zero builds these to run fifteen to twenty years and supports parts for a long time, so fixing one of these on a structurally good cabinet is almost always the right call. It is also far less disruptive than the cabinetry and panel work a full built-in replacement drags in with it.
Where the decision gets closer
The expensive fault is the sealed system — a refrigerant leak or a failing compressor. On a newer Concord unit we put gauges on it, show you the pressures, and it is usually still worth repairing. On a twenty-year-old unit that has already had a hard inland-summer life, we will read the numbers with you and sometimes tell you it is time. We would rather lose the repair than sell you one that does not make sense for the cabinet you have.
Parts availability is the other swing factor. Most Sub-Zero parts are easy to source; a small number on older model runs are not, and that can tip a borderline unit toward replacement on its own.
How we keep the call honest
Every recommendation starts with a diagnosis, not a guess: model and serial off the tag, cabinet and freezer temperatures, airflow, and electrical or sealed-system readings as the fault requires. You see the evidence the recommendation rests on, and the $89 service call goes toward the repair if you go ahead.
If you are weighing a repair against a new built-in, call it in and let the readings decide. A clear diagnosis is worth far more than a number pulled from the unit's age.