A device and a method for defogging and/or defrosting a glazing unit of a motor vehicle with a partially or totally electric propulsion system is disclosed. The device comprises means (1) for cooling a coolant fluid, using at least one electric current source, and a thermal battery (2), the device being configured to allow, in certain phases, the cooling of the coolant fluid by the cooling means (1) and the storage of cold from the coolant fluid in the battery (2), and, in other phases, the release of cold from the battery (2) into the coolant fluid.