Dual refrigeration and the grille
Most Sub-Zero built-ins use dual refrigeration: separate cooling systems for the refrigerator and the freezer, each with its own evaporator and controls. When one section warms while the other is fine, we already know which system to look at. Newer models also have a service mode in the control panel that shows temperatures and stored faults. It's one reason a Sub-Zero is easier to diagnose than most built-in refrigerator repair jobs.
Built-ins push heat out through a grille at the top or bottom. Dust on the condenser behind that grille is the single most common reason a Sub-Zero runs long and warm, especially in kitchens with pets or recent construction. Cleaning it is part of every Sub-Zero visit.
We repair Sub-Zero units in place. The grille, panels and cabinetry stay protected, and if the unit must slide out, we do it on floor protection with the right tools. Model-specific parts are matched to the serial number and quoted in writing before we order them.