Abstract: In the control device 12 of the indoor unit 11, a plurality of communication means 14a to 14c having different communication speeds; communication speed recognizing means 18 for recognizing whether or not a communication line 15 from an outdoor unit 10 is connected to any of the communication means, from the communication speed of the control information signal; and communication means confirmation means 18 for confirming the communication means that performs the following communication based on the recognized communication speed, are provided. According to this, it is possible to recognize the communication speed of an input signal without providing a manual changeover switch. Therefore, it is possible to solve at least one or more of the problems that the installation work is complicated, that a setting error of the changeover switch is likely to be generated, and that the product prices increase.

Abstract: In the control device 12 of the indoor unit 11, a plurality of communication means 14a to 14c having different communication speeds; communication speed recognizing means 18 for recognizing whether or not a communication line 15 from an outdoor unit 10 is connected to any of the communication means, from the communication speed of the control information signal; and communication means confirmation means 18 for confirming the communication means that performs the following communication based on the recognized communication speed, are provided. According to this, it is possible to recognize the communication speed of an input signal without providing a manual changeover switch. Therefore, it is possible to solve at least one or more of the problems that the installation work is complicated, that a setting error of the changeover switch is likely to be generated, and that the product prices increase.

Abstract: The present invention relates to a method for producing a fluoroalkylsulfonic acid anhydride represented by a general formula of (C.sub.n F.sub.2n+1 SO.sub.2).sub.2 O where n is an integer ranging from 1 to 8. This method includes a step of (a) reacting diphosphorus pentoxide with a fluoroalkylsulfonic acid represented by a general formula of C.sub.n F.sub.2n+1 SO.sub.3 H where n is an integer ranging from 1 to 8, in a fluorine-containing solvent, thereby to form the fluoroalkylsulfonic acid anhydride in the fluorine-containing solvent. A fluoroalkylsulfonic acid anhydride produced by this method is high in purity and yield.