Acson Air Conditioner Error Codes Acson Air Conditioner Error Codes A1 Indoor PCB ERROR A3 Drone Pump ABNORMAL A5 ANTIFREEZE (cooling) / heat accelerator overheating (heating) A6 Indoor Fan Motor Atal AH Electrical AIR Cleaners AB C4 INDOOR HEAT EXCHANGER (1) THERMISTOR SHORT / OPEN C5 INDOOR HEAT EXCHANGER (2) TI-IERMISTOR SHORT / OPEN C7