What's wrong with Norton mid mountain air coming out of d5

Norton Zhongshan air out d5 means communication failure. When the indoor unit (or outdoor unit) does not receive the correct signal sent by the outdoor unit (or indoor unit) for 3 consecutive minutes, a communication failure is generated and protection shutdown. Communication failure, the indoor unit shows E6, indoor "running" indicator light off 3S blinking 6 times, the indicator flashes light 0.5S off 0.5S. If the communication is back to normal, and the compressor stops for 3 minutes, the whole machine is allowed to return to normal allowed. Fault range: indoor electronic control, outdoor electronic control, indoor and outdoor connecting line group, external electromagnetic interference.