GREE              Duct type Ducted Type Split Air-Conditioner Units 
90 
Troubleshooting: 
Yes
No
No
“b9”heat exchanger 
outlet temperature 
sensor error
Is the terminal between 
mainboard and ambient temperature 
sensor loose or any foreign objects 
inside the terminal?
If it is loosened or there are 
foreign objects, retighten it 
after treatment.
Check if the temperature 
sensor is abnormal
Yes
Replace temperature 
sensor
Check if the circuit is 
abnormal
Yes
Replace the main 
control board
 
“C2” driven communication malfunction between main board and inverter compressor 
Fault display: the main board of outdoor unit and indoor unit will display  . 
Applicable model: all outdoor units. 
Judgment condition and method for the fault
:The outdoor unit cannot detect the data of inverter 
compressor drive board in 30s, then it will give alarm. 
Possible reason
: 
1)  The communication cable is not correctly connected. 
2)  The inverter compressor drive board is abnormal. 
3)  The main board is abnormal. 
Troubleshooting
: 
1)  Check if the cable connecting the control board and the compressor's drive board is loose. 
If yes, reconnect it; 
2)  Check if the cable connecting the control board and compressor's drive board is broken. If 
yes, replace the cable; 
3)  Check the contact of the communication cable connecting the control board and 
compressor's drive board; 
4)  Replace the control board. If the fault is solved, the control board is faulty. Replace the 
compressor's drive board. If the fault is solved, the compressor's drive board is faulty.