Bosch Fridge Freezer Not Freezing — Fix

What Does This Error Mean?

A Bosch freezer that is not freezing is usually caused by a defrost system failure with ice blocking the evaporator, or a failed evaporator fan. Unplug the fridge and manually defrost for 24 hours — if freezing resumes, the defrost system has failed.

Affected Models

Bosch Serie 2 Fridge-Freezer
Bosch Serie 4 Fridge-Freezer
Bosch Serie 6 Fridge-Freezer
Bosch Serie 8 Fridge-Freezer
Bosch NoFrost Refrigerator

Common Causes

Defrost heater or thermostat failed — ice blocking the evaporator coils on NoFrost models
Evaporator fan motor failed — cold air not circulating
Door gasket worn — warm air entering the freezer
Temperature control set too warm accidentally
Compressor not running at full capacity

How to Fix It

Check the temperature setting.

Confirm the freezer is set to -18°C. On dial-controlled models, ensure the dial is at the midpoint or higher. An accidental bump of the dial is a common and easily overlooked cause.
Manually defrost the freezer.

Unplug the fridge and remove all items from the freezer. Leave both compartment doors open for 24 hours. Place towels at the base to absorb melt water. Restart and monitor — if freezing resumes, the NoFrost defrost system has failed.
Check the evaporator fan.

After defrosting, remove the rear panel inside the freezer compartment. Close the freezer door (pressing the door switch manually). The fan should start running within 30 seconds. A silent fan with a running compressor indicates a failed fan motor.
Inspect the door gasket.

Run your hand around the freezer door seal with the door closed. Any airflow felt around the seal means the gasket is worn and warm air is entering. A worn gasket on a freezer causes gradual warming and ice cream going soft before the temperature alarm triggers.

When to Call a Professional

If manually defrosting restores freezing but the problem returns within days, the defrost heater, thermostat, or defrost control has failed and needs professional replacement.