Panasonic Air Conditioner Repair Analysis; 5P air conditioner does not start, no display after power is supplied.

Panasonic Air Conditioner Repair Analysis: 5P air conditioner does not start, no display after power is supplied.

Fault Phenomenon: The measured power supply voltage is normal, the phase sequence is correct, but the machine does not start, and there is no display after power is supplied.

Repair Process: The installation location of this unit is at a mobile base station. The service personnel replaced all the electrical control spare parts on-site multiple times without resolving the issue. After on-site inspection, it was found that this machine has remote network control. When the QMS remote module was disconnected, the machine could display, but the room temperature showed as 0 degrees, and it still would not start. After measuring, the 5V voltage at the third pin of the 7805 on the wired controller circuit board was only around 4.1V. However, when the QMS remote module was connected, the voltage immediately dropped to about 2.9V. The voltage at the first pin of the 7805, which should be around 12V, was only about 6V. The voltage at the primary side of the transformer was 210V without load, but as soon as the load was connected, it dropped to around 170V. It was found that this was caused by poor connection of the neutral wire at the user's power source.

Repair Measures: After rewiring, the test run was normal.

Summary: The hardware of Panasonic air conditioners generally does not have problems. During repair, one should not blindly replace parts without understanding the situation. There should be a logical troubleshooting approach to avoid unnecessary expenses and trouble in applying for unneeded spare parts.

Article Source: http://blog.sina.com.cn/songxiakt