Some issues can be resolved without any maintenance to the unit, check the chart below to see if there is a suggested solution to the problem before calling for service. Comfortaire AC Error Codes and Troubleshooting Glossary of Error Codes and Their Meanings: Error Codes Meaning E1 High Pressure Protection E2 Shutdown for Whole Unit AntiFreeze Protection E3 Low Pressure Protection E4 High Discharge Temp Protection E6 Communication Error E9 Indoor Unit Water Full Error Fo Refrigerant Recovery Mode F3 Outdoor Ambient Temp Sensor Error F4 Outdoor Mid-Coil Temp Sensor Error F5 Outdoor Discharge Air Temp Sensor Error F7 Oil Return for Cooling H1 Forced Defrosting H2 Oil Return for Heating or Defrosting H3 Compressor Overheat Protection H5 IPM Protection H7 Motor Desynchronizing Hc PFC Error Lc Startup Failure LA DC Fan motor Error Ld Phase Loss LE Compressor Stalling LF Over-Speed P0 IPM Reset P5 Compressor Current Protection P6 Communication Error between the Inverter Drive a...