Samsung HH175EZM Service Manual page 73

Troubleshooting
12-3-4 Communication error during the operation
Outdoor unit display
Indoor unit display
How to determine
Reason of error
Check the display after
pressing the reset key on outdoor PCB
When tracking, is there any
indoor answer from display part?
Measure the 2 lines of outdoor side
by scope after removing the
communication line connecting from
outdoor unit to indoor unit.
At this time, is the voltage
between lines rectangular wave over DC±0.7V
like below figure?
After connecting again the communication
line connecting from outdoor unit to indoor unit,
remove the communication
connector on indoor unit PCB, and find the
indoor unit preventing communication
through connecting the communication
connectors each by each, and then replace
the indoor unit PCB after line check.
+0.7V
-0.7V
12-9
(Communication error during the operation)
(Operation) (Timer)
Disconnection and short of communication lines
Communication error between the indoor unit and outdoor unit.
Yes
Yes
Good
(Airflow) (Filter)
Multi type
After 2 minutes, check if PCB address
setting of indoor unit displayed the
communication error among indoor units are
No
overlapped or not.
(If the indoor unit address is overlapped, the
communication error is occurred.)
- In this case, the communication error is
occurred to over two indoor units set
wrong.
exchange the indoor unit PCB after
communication line check.
No
Replace PCB after checking
the outdoor unit communication line
If address is not fault
and connector
Bad
Samsung Electronics