An household appliance of a combined type, in particular a refrigerator-freezer, comprising: a first refrigerating unit and a second refrigerating unit, both served by a single cooling circuit and fluid-dynamically connected to each other by an air passage conduit; the cooling circuit comprising: a compressor, an evaporator, a condenser or radiator and an expansion valve, serving both said refrigerating units (2,4), the evaporator being arranged close to the second refrigerating unit, intended in use to remain at sub-zero Centigrade temperatures; the household appliance further comprising control means of the temperature inside the refrigerating units (2,4), comprising a thermostat, a temperature sensor connected to the thermostat and arranged near the evaporator and control means of the cooling circuit controlled by the thermostat and comprising a control unit, not necessarily electronic, and said air passage conduit; said control means further comprising a control device of the temperature inside the first refrigerating unit, the control device comprising: a supporting body adapted to be in use arranged along said air passage conduit; motorised means for selective interception of said air passage conduit, carried by said supporting body; electronic control means of said selective interception motorised means carried directly aboard of said supporting body; and an additional electronic temperature sensor which is operatively and directly connected to the electronic control means of the selective interception motorised means, and which is arranged so as to detect the temperature along the connection conduit, towards the said first refrigerating unit or directly within the first refrigerating unit; said control device being characterized by having ventilator means, operated by said electronic control means of the selective interception motorised means, carried directly aboard of said supporting body, so as to be in use arranged inside said passage conduit and adapted to selectively ensure a circulation of air by forced convection between said first and second refrigerating unit when said selective interception motorised means are in an operative position in which they leave said air passage conduit at least partially open. a supporting body adapted to be in use arranged along said air passage conduit; motorised means for selective interception of said air passage conduit, carried by said supporting body; electronic control means of said selective interception motorised means carried directly aboard of said supporting body; and an additional electronic temperature sensor which is operatively and directly connected to the electronic control means of the selective interception motorised means, and which is arranged so as to detect the temperature along the connection conduit, towards the said first refrigerating unit or directly within the first refrigerating unit; said control device being characterized by having ventilator means, operated by said electronic control means of the selective interception motorised means, carried directly aboard of said supporting body, so as to be in use arranged inside said passage conduit and adapted to selectively ensure a circulation of air by forced convection between said first and second refrigerating unit when said selective interception motorised means are in an operative position in which they leave said air passage conduit at least partially open.