Carrier Air Conditioning Error Code Carrier Air Conditioning Error Code EO-(OL 1 Time)Indoor unit EEPROM parameter error. E1-(OL 2 Time)Indoor / outdoor units communication error. E3-(OL 4 Time)The speed of the indoor fan has gone out of control. E4-(OL 5 Time)Indoor room temperature sensor T1 open circuit or short circuit.       E5-(OL 6