E 1 code refers to compressor overheating, excessive current, exhaust overheating and module protection; E2 represents the anti-freezing protection for starting the indoor unit; E3 and E4 refer to compressor low voltage protection, compressor exhaust temperature protection, and open and short circuit of indoor unit temperature bulb; E5 stands for communication failure between undervoltage protection and indoor and outdoor units, and the number 2 stands for abnormal control loop; 3 refers to the lack of phase of three-phase power supply; E6 refers to electrostatic dust removal protection; E7 refers to mode conflict; E8 refers to high temperature protection; E9 refers to cold air protection; E0 is the frequency reduction of the AC voltage of the whole machine; H6 means no indoor motor feedback, and C 1 means fault arc protection; C2 refers to leakage protection; C3 refers to wrong connection protection; C5 stands for jumper cap fault protection; C6 refers to the air conditioning socket without ground wire; F0 refers to fluorine deficiency or blockage protection of the system; F 1 is the open circuit and short circuit of the indoor ambient temperature sensor, similar to E3 and E4. F4 refers to the outdoor condenser bulb open circuit and short circuit; F5 refers to the outdoor exhaust temperature sensor open circuit and short circuit; F8 refers to the frequency reduction caused by excessive current; F9 refers to excessive reduction of exhaust frequency; U5 refers to the current overhaul fault of the whole machine.