We report on the estimation technology for anomaly cause and identification technology for inner units with anomaly expansion valve of multi-split air conditioning systems for buildings. We had been developed the anomaly sign detection based on equipment capacity statistics and the anomaly cause estimation method based on the anomaly equipment capacity statistics. However, this method was limited to estimating types of faulty equipment. In this paper, target is anomaly expansion valve of inner units because of high failure frequency and estimation difficulty due to many inner units. We developed the anomaly cause estimation method for inner units with anomaly expansion valve based on the two dimensional distribution density images using anomaly equipment capacities and the expansion valve open lock rate. We verified proposal methods using for two multi-split air conditioning systems for buildings. As a result, our proposal methods were valid because the inner units with anomaly expansion valve by our estimation results and site log matched.

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