Samsung AVMKH020EA0 Service Manual page 235

8
Troubleshooting
8-2-52. Communication error between the outdoor unit and MCU
Outdoor unit display
Indoor unit display
Judgment method
Causes
Is OK the connection between
the outdoor unit and communication
Press the reset(K3) outdoor unit PCB
and check the display part.
Is there any response of MCU or
indoor unit from the display part on tracking?
MCU address: Fb-FE
Remove the communication line from the
outdoor unit to MCU, and measure 2 lines of
indoor unit side by use of scope.
Is the voltage of
2 lines square wave of
After connecting the communication line connected
from the outdoor unit to MCU again, remove all
communication connectors of MCU and outdoor unit.
And then connect it one by one to find a communication
obstacle and replace PCB after checking the
communication line.
(Operation) (Timer)
- When it is not communicated between the indoor unit and outdoor unit during the operation
- Communication error between the outdoor unit and MCU
connector?
Yes
Yes
Yes
Yes
DC ±0.7V?
Yes
(Fan) (Filter) (Removing frost)
No
Restart after connecting a
connector to PCB.
No
Check again the communication line
connected with MCU.
If there is no error after checking the
communication line, replace MCU PCB.
No
If there is no error after checking the
communication line and connector of
outdoor PCB, replace MCU PCB.
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