Cause and solution:

1, to judge whether the ambient temperature is too low.

2. To judge whether it is a control fault or a system fault, you can first short-circuit the LPP plug on the main control board and the zero line N on the main board. If the indoor unit is running normally, it can be determined that there is no problem with the main board or display board of the indoor unit, and the fault occurs in the connecting wire, plug or low-voltage switch of the outdoor unit.

3. Connect the external machine line and plug, set the multimeter on the ohm gear, connect one probe to the LPP protection line unplugged from the motherboard, and connect the other probe to the neutral line N. If the resistance value is 0, the fault is on the low-voltage switch, and vice versa. The fourth step is to judge whether the system leaks fluorine or is blocked by the pressure gauge.