Lennox AC Error Codes and Troubleshooting

Error Codes	Trouble
E0	EEPROM parameter error
E1	Indoor/outdoor units communication protection
E2	Zero-crossing signal error
E3	Indoor fan speed out of control
E5	Open or short circuit of outdoor temperature sensor or outdoor unit EEPROM parameter error
E6	Open or short circuit of room or evaporator temperature sensor
E7	Outdoor fan speed out of control
P0	IBM malfunction or IGBT over-strong current protection
P1	Over voltage or too low voltage protection
P2	Temperature protection of compressor top
P4	Inverter compressor drive error

Lennox Split AC Error Codes

If there is an error occurring during the operation of the system, the error code will be displayed on the LCD, as show in Fig.5.1. If multi errors occur at the same time, their codes will be displayed circularly.

Lennox Split AC Error Codes

Note: In event of any error, please turn off the unit and contact the professionally skilled personnel.

Meaning of Each Error

F1: Return air temperature sensor open/ short circuited

P6: Drive board communication error

F2: Evaporator temperature sensor open/ short circuited

H3: Compressor overheating protection

b5: Indoor unit liquid valve temperature sensor open/short circuited

LP: Indoor and outdoor units unmatched

b7: Indoor gas valve temperature sensor open/ short circuited

dn: Communication line misconnected or expansion valve error

P7: IPM temperature sensor open/short circuited

E7: Running mode conflict

F3: Outdoor ambient temperature sensor open/ short circuited

Fo: Pump-down

F4: Outdoor unit condenser mid-tube temperature sensor open/short circuited

C5: Jumper error

F5: Discharge temperature sensor open/ short circuited

H1: Forced defrosting

E6: Indoor and outdoor communication error

Lc: Compressor startup failure

PL: DC bus under-voltage protection

E4: High discharge temperature protection

PH: DC bus over-voltage protection

E8: Overload protection

U1: Compressor phase current sensing circuit error

E5: Whole unit over-current protection

HE: Compressor demagnetization protection

P5: Over phase current protection

Hc: PFC protection

H7: Compressor desynchronizing

P8: IPM Temperature Protection

H5: IPM Current protection

L9: Over-power protection

Ld: Compressor phase loss/reversal protection

F0: System charge shortage or blockage protection

F8: Frequency restricted/reduced with whole unit current protection

PU: Capacitor charging error

IPM: Frequency restricted/reduced with

En: Current protection

E1: High pressure protection

F9: Frequency restricted/reduced with high discharge temperature

Lennox AC Remote Control

E3: Low pressure protection

FH: Frequency restricted/reduced with antifreezing protection

LE: Compressor stalling

F6: Frequency restricted/reduced with overload protection

LF: Over-speeding

EU: Frequency restricted/reduced with IPM temperature protection

PF: Drive board temperature sensor error

E9: Indoor unit full water error