--- title: "Freezer not freezing" description: "Sub-Zero freezer not freezing — a freezer running warm, frosting heavily, or holding a temperature that looks right on the display and is not right in the…" url: "https://subzeromiami.support/symptoms/freezer-not-freezing/" date_modified: "2026-08-18" Appliance type: "Freezers, Undercounter & drawers" --- # Sub-Zero freezer not freezing ### The fastest diagnosis is the code A code on the display answers this quicker than any description can — it says whether the board is watching a load behave badly or a sensor read something impossible. Photograph it before it clears. ### Frost is a symptom, not a cause Heavy frost almost never means the freezer is running too cold. It means warm air is getting in or the defrost cycle is not completing: a door seal, a defrost heater, a thermistor reading wrong, or a drain that has iced over. Each of those is a different repair at a different figure, which is why the diagnosis comes first. ### Dual refrigeration changes the reading On a cabinet with two sealed systems, a freezer that will not hold while the refrigerator side is perfect is useful information: it points at one system rather than at anything shared. Tell us which side is misbehaving when you book and we will come prepared for that one. Frost, or not cold enough What it usually means Ice cream soft, everything else fine Heavy frost on one shelf Display reads correctly, contents say otherwise The fastest diagnosis is the code A code on the display answers this quicker than any description can — it says whether the board is watching a load behave badly or a sensor read something impossible. Photograph it before it clears. Frost is a symptom, not a cause Heavy frost almost never means the freezer is running too cold. It means warm air is getting in or the defrost cycle is not completing: a door seal, a defrost heater, a thermistor reading wrong, or a drain that has iced over. Each of those is a different repair at a different figure, which is why the diagnosis comes first. Dual refrigeration changes the reading On a cabinet with two sealed systems, a freezer that will not hold while the refrigerator side is perfect is useful information: it points at one system rather than at anything shared. Tell us which side is misbehaving when you book and we will come prepared for that one. A door that no longer closes square Even frost across the compartment points at the door rather than at the coil. Warm air getting in continuously is the commonest reason a freezer stops holding. Airflow blocked from inside A compartment packed tight enough to block the internal vents will not hold temperature however well the system is working. It costs nothing to check and it happens often. A defrost heater or thermistor Local frost concentrated on one shelf or on the coil, rather than even frost, is what separates this from a door problem. A drain that has iced over Water that cannot leave freezes where it stands, and the ice then blocks the airflow that would have cleared it. It compounds until somebody looks. One sealed system of two A freezer that will not hold while the refrigerator side is perfect points at one system rather than at anything shared. Say which side when you book. Look at where the frost is Even frost across the compartment points at the door. Frost concentrated on one shelf or on the coil points at the evaporator. It is the same difference a technician looks for. Check the door closes square And that the seal grips along its whole length, not just at the handle. Warm air getting in continuously is the commonest reason a freezer stops holding. Check nothing is blocking the vents A compartment packed tight will not hold temperature however well the system is working. It costs nothing to move things and wait a day. Then book the visit Say which side is misbehaving if the cabinet has two, and whether this started after a power cut — it changes the likely answer entirely. --- **[Read full article: Freezer not freezing](https://subzeromiami.support/symptoms/freezer-not-freezing/)**