Lennox MPA012S4S-1L Service Manual page 134

Single zone outdoor units display fl ash codes on the main board. The main board is accessed through the top
of the unit. Indoor units will display more detailed fault codes. See Section 13.4 for troubleshooting indoor unit
fault codes
main control board
NOTE Slow flash----Flashing at 1Hz Fast flash----Flashing at 2Hz
LED display
IPM board
(comp.driver)
Blue LED Green
Red LED
Slow flash OFF
LIT
LIT
Fast flash OFF
LIT
Fast flash
Fast flash
Fast flash
Fast flash
Fast flash
Fast flash
LIT
Fast flash
OFF
Fast flash
Fast flash Fast flash
IDU--Indoor unit ODU---Outdoor unit
Error Description
Error Description
LED
Standby
LIT
Normal operation
OFF
IDU & ODU communication error or
ODU temp.sersor error or
ODU EEPROM error or
LIT
Outdoor fan motor speed out of control or
Compressor top temp.Switch open
DC bus voltage too high/
LIT
too low protection
Driver EEPROM error
LIT
Driver chip start-up failure
OFF
Driver phase loss protection,or
Driver zero speed protection, or
Fast flash
PWM synchronization failure
IGBT over-current/IPM over-current
Fast flash
Control board chip communication error
Lennox Mini-Split Service Manual / Page 134