Lennox MPA012S4S-1L Service Manual page 195

All indoor units provide fault code information with either a digital LED display or with fl ash codes.
NOTE
Display
Indoor unit EEPROM error
Communication error between indoor unit and outdoor units
Indoor fan speed error
Indoor Return air temperature sensor error
Indoor coil temperature sensor error
Low refrigerant
High water level alarm
Outdoor current overload sensed
Outdoor ambient temperature sensor error
Outdoor coil temperature sensor error
Compressor discharge temperature sensor error
Outdoor unit EEPROM error
Outdoor unit fan speed error
Inverter module IPM error
High or Low voltage protection
Outdoor unit low temperature lockout
Compressor drive error
Mode conflict
Compressor high-pressure or low-pressure switch open
Indoor Unit Sticker Shown - ALL Indoor Units 09/24
Display
flash , light, X extinguished
Indoor Unit Sticker Shown - ALL Indoor Units 09/30-48
Lennox Mini-Split Service Manual / Page 195