Acson AC Error Codes and Troubleshooting The code indication changes as shown below, and notifies with a long beep. Wall Mounted AC Inverter Unit Error Codes Operation / Faulty Indication E1 Room air sensor contact loose / short. Check room sensor connection / change room sensor E2 Indoor coil sensor contact open. Check indoor coil sensor connection / change indoor coil sensor E3 Outdoor coil sensor contact open. Check outdoor coil sensor connection / change outdoor coil sensor E4 Compressor overload protection / Indoor / Outdoor coil sensor short. If running ampere highly increase, change the compressor. If not, replace the coil sensor E5 Gas leak. Check for leakage & repair / Top up refrigerant E6 Pump fault. Clear the clogging at drain pipe. If pump is not working, change the pump E7 Outdoor coil sensor exist (MS model). Remove outdoor coil sensor E8 Hardware error (tact switch pin short). Check for the tact switch pin condition E9 No Feedback from indoor fan. Check indoor...