Samsung AC026JNNCEH Service Manual page 37

4-3-4 Communication error after finishing Tracking
Indoor unit display
Symptom
Failure
Is there a response from the indoor PCB?
(LED01 (RED) is not ON)
Remove the communication cable
connecting the outdoor unit to indoor unit,
and measure the signal on LINE 2 of the
outdoor unit with a scope
voltage waveform between the lines square
wave with amplitude over ±0.7V as shown
in the following picture?
Reconnect the cable connecting
the outdoor unit to the indoor unit
If the communication still doesn't work,
replace the indoor unit PCB.
+0.7V
-0.7V
4-18
X (Operation) (Defrost)
Communication error between the indoor and outdoor unit for two minutes
Communication error between the indoor unit and outdoor unit
Yes
In this case, is the
Yes
and restart the unit.
Good
(Timer) X (Filter)
No
LED01
No
Check the communication cable and
replace the indoor unit PCB
Check the communication
cable in the outdoor unit PCB
and replace the PCB
Bad
Samsung Electronics