Panasonic, Beijing Panasonic Air Conditioning Repair Center 5P cabinet air conditioner, frequently burns AC contactors.
Fault phenomenon: Initially, no cooling occurs, the yellow light is on, and the AC contactor burns continuously.
Article source: Beijing Panasonic Air Conditioning Repair Phone http://blog.tianya.cn/blogger/blog_main.asp?BlogID=3484683.
Analysis and Maintenance: After replacing the AC contactor, upon turning on the machine, measurements were taken of the three-phase four-wire voltage inside the unit as well as the AC outputs of the control transformer (12V, 6.3V, 12.3V) and the DC voltages (9V, 6V), all of which were normal. No abnormalities were found when starting the machine; the three-phase current of the compressor was balanced, and the cooling function was normal. However, after two days of normal operation, the fault reoccurred, indicating a problem with the circuit components. Upon inspection, it was discovered that the rectifier diode D3 (IN4003) in the over/under-voltage protection circuit had poor thermal stability, causing instability in the DC voltage.
Solution: Replacing D3 with the same model resolved the fault.