Midea V8 VRF Series Service Manual page 68

6.1.20 C71 - Abnormal communication between AHU Kit slave unit and master unit
Note: When multiple AHU Kits are connected in parallel, the master AHU Kit (referred to as the master) communicates with the
ODU, and the slave AHU Kit (referred to as the slave) communicates with the master control box.
Error display
Master unit and slave unit: stop. Other IDUs of the same system: operate normally.
Error impact
ODU of the same system: operate normally.
If the main control board of the master unit has lost communication with the main control board of
Error trigger
the slave unit for 2 min;
Error recovery
Automatic recovery
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Possible cause
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Troubleshooting
Note: The error code can be queried after the slave is connected to the display box (during field
service, the display box can be temporarily removed from the master unit and connected to the
slave unit)
Digital display
The slave unit's main control board is damaged.
The master unit's main control board is damaged.
Communication cables are loose or the communication port is faulty.
Communication cables have short-circuited or been cut off.
C71
Are communication cables
loose or communication ports
wrong?
No
Is the communication
cable disconnected or short
circuited?
No
Is the fault cleared after
replacing the main control
board of the slave unit?
No
Replace the main control
board of the master unit
V8 VRF Indoor Units
Display position (master)
Display box or wired controller
Properly connect the cables
Yes
and ensure they are connected
to the right ports
Yes Replace the communication
cable and properly connect the
cable
Yes
Replace the main control
board of the slave unit
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