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You will need a volt meter to do the checks. The inverter will have 2 harnesses. The bigger one should have 120 volts going to it. The small one should have about 5 volts going to it. If that checks out, do a continuity check on the compressor terminals, all 3 ways. They should all be equal. If all equal, replace inverter. If readings are way off, or grounded, replace compressor. If no 120 or 5 volts to inverter, replace main board. You can parts needed at appliancepartpros.com, just enter in the model#. If this information has assisted you, please give a goo to great rating for doing so. You can always respond back if needed. thank you