1. Low voltage protection may be caused by low ambient temperature: In this case, it is recommended to use a temperature measuring gun to detect the ambient temperature for confirmation. If the ambient temperature is normal, it is recommended to contact an after-sales engineer to check whether the temperature detection equipment of the air conditioner is abnormal. 2. It may be a control fault or system fault: In this case, the LPP plug on the main control board can be short-circuited with the neutral line N on the main board. If the indoor unit operates normally, it can be determined that there is no problem with the indoor unit mainboard or display board. The fault occurs in the indoor and outdoor unit connecting wires, plug connectors or outdoor unit low-voltage switch. 3. It may be a wiring problem or a low-voltage switch problem: In this case, you can connect the external connector and plug, adjust the multimeter to the ohm setting, and connect a probe to the LPP protection line unplugged from the motherboard. , the other probe is connected to the neutral line n. If the resistance value is 0, it means that the fault is on the low-voltage switch, otherwise it is a circuit problem. Finally, the pressure gauge can be used to determine whether the system is leaking or clogged.