The invention relates to an adjustment device, actuated by an external force, for adjusting a seat or a window lift of a motor vehicle. Said device comprises an adjustment drive, a control device for controlling the drive and an operating device for actuating the control device. According to an adjustment method, at least one control signal that is specific to the direction of adjustment is transmitted from the operating device to the control device via a common air interface. The operating device is supplied with power via the common air interface and the adjustment drive can be controlled by the control device using the control signal that has been transmitted via the common air interface.