Very quiet 12 V refrigerator double ventilator, specially designed for mounting on existing ventilation grilles to transport waste heat, e.g. from refrigerators, to the outside more quickly and thus improve cooling performance. The ventilator, which is waterproof and dustproof to IP55 standard, can be switched manually in 6 stages via the external speed controller or operated automatically via sensor-controlled automation in the temperature range from 20 °C (switch-on point) to 45 °C (maximum speed). The ventilators are equipped with overvoltage protection integrated in the control unit, which allows safe operation in the 12 V on-board power supply.