Freezer Not Freezing? Common Causes and What to Do

A freezer that won’t freeze puts everything inside it at risk, so it’s worth acting quickly. The good news is that most cases come down to a handful of causes, and several of them you can check yourself in a few minutes.

Below we go through them in the order we’d check them on a service call: the quick checks first, then frost and the defrost system, the fans and coils, and finally the compressor and sealed system.

Start with the quick checks

• Temperature setting. A freezer should sit at -18°C (0°F) or colder. Dials get bumped, especially when the freezer is packed.
• Door and seal. Close the door on a sheet of paper. If it slides out easily, the gasket may be worn or the door may be out of line.
• Blocked vents. Packed food in front of the air vents stops cold air circulating. Leave a few centimetres of space around them.
• Warm food or a fresh start. A freezer that was just defrosted, moved or loaded with warm food can take up to 24 hours to get back down to temperature.
• A cold garage. Fridge-freezers in an unheated garage can stop cooling the freezer in winter, because the thermostat in the fridge section rarely calls for cooling.

Frost on the back wall: the defrost system

Most frost-free freezers run a short defrost cycle several times a day to melt frost off the evaporator coil behind the back panel. When a part of that system fails, frost builds up until it blocks the airflow, and the freezer slowly warms even though the compressor is running.

The usual suspects are the defrost heater, the defrost thermostat and the defrost timer or control board. A technician tests each one and replaces the part that has failed. As a stop-gap, you can unplug the freezer for 24 hours with towels underneath to melt the ice, but if it frosts up again within a few weeks, the defrost system needs a repair.

The evaporator fan isn’t moving air

The evaporator fan pushes cold air from the coil into the freezer and, in most models, through to the fridge. If the fan stops or ice jams the blades, the coil stays cold while the compartment warms up.

• No air coming from the vents when the door switch is pressed
• Grinding, squealing or rattling from the back of the freezer
• Frost building up around the fan cover

If ice is blocking the blades, the defrost system is usually the real cause. If the fan motor has failed, it’s a common, quick replacement.

Dirty condenser coils or a stopped condenser fan

The condenser coils, under or behind the unit, release the heat taken out of the freezer. When they’re coated in dust or the condenser fan stops, the freezer runs longer and can’t reach temperature. Clean the coils about every six months; left dirty, they shorten the life of the compressor. Warm sides on the cabinet can also point to the condenser.

A faulty sensor or control

A temperature sensor (thermistor) or control board that misreads can make the freezer stop cooling too early, or run all the time without reaching temperature. These faults are confirmed with a meter, not guessed, so this is one to leave to a technician.

Start relay, compressor or a refrigerant leak

If you hear a click every few minutes and the compressor doesn’t keep running, the start relay or overload is often the culprit, and it’s an inexpensive part. If the compressor itself has failed, or the sealed system has a refrigerant leak, both sections usually warm up slowly over days.

Compressor replacement and sealed-system repairs are specialist jobs. We do them in the home, including the inverter compressors in many LG and Samsung refrigerators, and the technician will tell you honestly whether the repair is worth it for your unit’s age.

Chest freezers and upright freezers

Manual-defrost chest and upright freezers don’t have a defrost system, so frost builds up over time. Defrost them when the ice is about 6 mm (a quarter inch) thick. If one stops cooling altogether, check the outlet and the dial first; the start relay and thermostat are the most common failed parts.

What’s safe to check yourself

• Confirm the setting and use a freezer thermometer to check the real temperature.
• Clear food away from the vents and close the door on paper to test the seal.
• Vacuum the condenser coils with the freezer unplugged.
• Listen for the fans and the compressor. Note any clicking, buzzing or silence; it helps the diagnosis.

When to call a technician

If the freezer isn’t back to -18°C within 24 hours of the quick checks, or you see heavy frost on the back panel, book a repair. Keep the door closed in the meantime: a full freezer holds its temperature for about 48 hours, a half-full one for about 24. You’ll get a written price before any work starts, and same-day visits are available whenever a technician and parts are free.

Frequently Asked Questions