Method for converting a blow molding machine and blow molding machine

A method for converting a blow molding machine for producing plastic containers from preforms by blow molding in container-producing normal work cycles in a plurality of exchangably-installed blow molds, the blow molding machine having a plurality of molds which are rotatingly movable during a normal work cycle and heated to a heat-set operating temperature, each blow mold being adjustable between open and closed states and defining at least one mold cavity having internal mold cavity surfaces and converting the blow molding machine by a mold change of the plurality of blow molds, the method comprising carrying out at least one simulated work cycle with the plurality of blow molds in an empty state for preparing the mold change in the blow molding machine, externally supplying and during the at least one simulated work cycle conveying a cooling medium at least substantially at the same time through all of the mold cavities of the plurality of blow molds and cooling the blow molds by the externally supplied cooling medium with respect to the heat-set operating temperature by heat discharge from the mold cavity surfaces.