Haier MVAH018MV2AA Service Manual page 43

[07] Communication abnormal between indoor and wired controller
If wiring of terminal A, B, C of
wired controller is proper
If the broken wire or port is
fixed improperly
If in group operation
If there is indoor unit
set as No. 0
If indoor unit is running
No
Yes
Yes
No
If there is indoor unit
No
set as No. 0
If there are multi indoors
set as No. 0
No
Yes
If LED2 on indoor PCB is ON,
Yes
which indicate the serial signal
sent to wired controller
If LED1 on indoor PCB is ON,
which indicate the serial signal
sent to wired controller
Modify the wiring
Modify the connection
No Set one indoor
unit as No. 0
Yes
No
Set one indoor
unit as No. 0
No
Yes
No
No
Check wired controller
PCB, if faulty, replace it
41
Set only one indoor
unit as No. 0
Check indoor PCB, if
faulty, replace it
Yes