The gasket seals the door against the cabinet. A hardened or torn seal lets warm, humid air in, which causes frost, constant running and condensation.
Brand repair hub
Sub-Zero Appliance Repair
Sub-Zero builds premium built-in refrigerators and freezer columns, now part of Sub-Zero Group alongside Wolf. Sealed-system and control work on these units is specialist work, and parts are model-specific.
Find the model plate
The rating plate is inside the refrigerator or freezer compartment, usually on the upper left interior wall.
Sub-Zero repair guides by appliance
Parts for Sub-Zero appliances
The defrost heater melts frost off the evaporator during the defrost cycle. If it fails, ice builds up, airflow stops and the freezer warms.
The evaporator fan moves cold air from the coil into the cabinet. A failed motor leaves the compressor running but the cabinet warm, and it often makes a bearing noise before it stops.
The start relay gives the compressor a momentary boost to start. When it fails, the compressor clicks, hums briefly and trips, and the cabinet warms.
The ice maker fills, freezes and dumps cubes on a timer. Failures show up as no ice, small or hollow cubes, or a maker that overflows.
The thermostat or thermistor tells the compressor when to run. A failed sensor makes the freezer run constantly or not at all, and the part is inexpensive compared with the compressor it protects.
Always order by the full model and serial number. A part that looks identical can differ in mounting, wattage or connector.