Cyclogic CL-MC02B Air Conditioning Inverter Compressor Phase Checker The "Inverter Phase Checker" is the perfect low-cost answer to a technician's problems when an inverter-controlled air conditioner fails. The difficulty lies in whether the compressor or the inverter is problematic – in which the Inverter Phase Checker can identify which is faulty. The supply connections are disconnected from the compressor, and are connected to this module. When the inverter is switched on, all six LED lights on the Inverter Phase Checker will light up Red, Yellow, and Green. If the inverter PCB is faulty, one or more of these lights will not switch on identifying the problem. - If all six lights are on, the inverter PCB is fine, and the fault is with the compressor. - If all LED lights are not on or one light is significantly dimmer than the rest, then the fault is with one or more of the output transistors on the PCB, or with the drive circuitry. The Inverter Phase Checker is small enough to carry in any toolbox and will save you time with a quick analysis. A kit of connection leads is attached to the Inverter Phase Checker. The three leads are 3ft. (1m) in length each and fitted with insulated ¼" female fasteners. Although small, it is not intended to be hand-held. All power supplies must be safely turned off while the module is being connected.