An apparatus for controlling a tempering device of a blow-molding machine for tempering at least one blow mold member of a blow mold or a blow mold member carrier to a target temperature, with a device for receiving a temperature actual value of the blow mold member or the blow mold member carrier, where the temperature actual value is measured by a temperature measuring device in the blow mold member or the blow mold member carrier, devices for receiving a temperature target value of the blow mold member or the blow mold member carrier, analyzing the received temperature actual value and the received temperature target value, calculating a setting value for the tempering device from the received temperature actual value and the received temperature target value, and transmitting the setting value to the tempering device.