The air conditioner has a cold compressor (50) with at least one connecting element to a drive, and a control device by which the drive revolutions and compressor revolutions are coordinated. The connecting element e.g. a belt (57) is part of the drive-side element (62) of the viscous coupling (54). The viscous coupling has at least one working chamber (7) filled with a viscous fluid, and at least one storage chamber (8) for the viscous fluid. The ratio of the degree of filling of these chambers can be set by the control device (58) via the setting device (59).
