Your Sub-Zero stopped cooling. Here is who may legally fix each likely cause.

The triage desk starts here because San Rafael geography does. Hillside lots in Glenwood and Country Club shed fine dust that the condenser fan pulls through the grille season after season, and a mat of it on the coil makes a healthy Sub-Zero run long, hot and eventually warm. Pet hair does the same work faster. The cabinet looks like a refrigeration failure; it is usually a cleaning failure.

The fix - clearing the coil, restoring grille clearance, confirming the temperature recovers - touches no refrigerant at any point, and it is the single most frequent resolution to a no-cool call in our route notes.

Fog is a diagnostic instrument in this city. A gasket that has gone soft or lost contact shows itself fastest in Peacock Gap and along the China Camp shoreline, where humid marine air condenses on the door frame and freezes into a frost line. Warm wet air leaking past the seal forces the unit to run continuously, and the symptom reads as not cooling even though the machine itself is healthy.

Gasket replacement, hinge adjustment and panel-square correction are mechanical work. The page on door gasket and cabinet seal repair shows how the leak is proven - not assumed - before a part is ordered.

When a defrost heater, terminator or defrost control fails, frost accumulates until air can no longer pass through the evaporator coil. Cooling fades gradually - often the fresh-food section first - and a full manual defrost temporarily cures it. That temporary cure is a clue worth writing down: it points away from the compressor and toward the defrost circuit.

Defrost components are electrical parts mounted around the coil. Replacing them takes panel access, a meter and patience - not refrigerant equipment.

Two fans move all the air this appliance owns. A failing evaporator fan starves the cabinet of cold air while the freezer may still hold; a failing condenser fan starves the machine of heat rejection and stretches every cycle. Both usually announce themselves - new bearing noise, intermittent stalls after door openings - before they quit outright.

Confirmation is a response test and an amp reading; the repair is a motor swap, with the refrigerant circuit untouched beside it.

A drifted thermistor or a confused board can mis-time cooling calls and defrost cycles until the cabinet warms with nothing mechanically wrong. The danger here is false certainty: a displayed code names a suspect, not a culprit. Sub-Zero error codes and alarms explains why the same code can come from a sensor, a harness, an airflow fault or a power event - and what verification looks like for each.

Board and sensor replacement is electronics work: connectors, resistance readings, model-specific service data. It demands discipline, not a federal credential.

If every cause above has been ruled out with evidence and the loop itself is the suspect, the rules of the visit change. Whenever a cause requires opening the loop, the person holding the tools must be certified - a federal condition in effect since November 14, 1994. Sealed-system causes call for a certified rating: your unit sits in the small-appliance class - production-sealed, five pounds of charge at maximum - which is Type I territory, though many technicians carry Universal, earned across the high-pressure (Type II) and low-pressure (Type III) sections plus a supervised Core.

A slow leak is a misfortune, not a crime - but service that lets the rest of the charge escape is: venting has been prohibited for CFC and HCFC refrigerants since July 1, 1992, and for substitutes such as R-134a since November 15, 1995. The law tolerates the trace amounts that escape during good-faith recovery; it does not tolerate a shrug. Beware the cut-rate recharge offer: anyone making it either holds certification - the only way to buy the gas for stationary equipment - or acquired their refrigerant outside the law.

What the certified visit actually proves, and in what order, is documented on the sealed-system page: how sealed-system suspicion is verified before any San Rafael quote names a compressor.

Whoever arrives must hold their own certificate: it is issued per person, and once earned it does not have to be earned again. The last triage rule: certify the person, not the logo. EPA's credential goes to technicians individually; a company name on a van proves nothing about it.

The verdicts above also shape cost: open-cause repairs carry ordinary labor, while sealed-system steps add recovery equipment and certified time. That split is visible in the published planning ranges - see what Sub-Zero repair costs in San Rafael before approving major work.

1. Fix the era first: Photograph the model and serial tag so the refrigerant era - R-12, R-134a or R-600a - is known before any cause is judged.
2. Record the split: Write down fresh-food and freezer temperatures, alarm timing and fan sounds before resets erase the history.
3. Run the open causes: Check condenser dust, gasket contact, defrost behavior, fan response and control readings - the five causes any competent hands may repair.
4. Demand evidence at the boundary: Allow sealed-system talk only after airflow, electrical and frost-pattern evidence has ruled the open causes out.
5. Verify the person: Before the loop is opened, confirm the individual technician holds a Section 608 certificate; the company name on the van settles nothing.