Why is a compressor dehumidifier almost ineffective below 10°C or 15°C?

The operation of a compressor dehumidifier is similar to that of a refrigerator. In fact, the condenser (the very fine lamella grid) is slightly colder than the ambient air. Thus, the water contained in the air condenses and flows into the tank. Below about ten degrees, these water droplets risk freezing instantly on contact with the condenser, and forming a block of ice at the back of the device. To avoid this, new generation dehumidifiers are equipped with a "defrost" or "anti-freeze" mode that will disconnect the compressor for a while (or longer if it is very cold). The air thus circulates at room temperature and the device does not freeze, but it is almost ineffective.