A refrigerator-freezer of the combined type comprises a first and a second refrigerating units and a single cooling circuit for both units, which are fluid-dynamically and reciprocally connected by an air passage conduit; the temperature inside the first unit is controlled by a device comprising motorised interception means of the passage conduit; electronic control means of the motorised interception means, directly carried aboard a supporting body adapted in use to be arranged along the passage conduit; an electronic temperature sensor operatively and directly connected to the electronic control means, carried aboard the supporting body; and ventilator means, carried aboard the supporting body, operated by the electronic control means of the motorised interception means for selectively ensuring circulation of air by forced convection between the first and second refrigerating units along the passage conduit.