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5.3  E1 (Indoor and outdoor unit communication error) 
Description: The indoor unit has not received feedback from the outdoor unit for 150 seconds, four consecutive times.
Recommended parts to prepare:
• Indoor PCB
• Outdoor PCB
• Reactor 
Troubleshooting and repair:
Power off, then restart the unit after 2 minutes.
Does a problem remain?
The unit is operating normally
NO
Measure Vs. (Vs is the voltage between S and N of 
outdoor unit. Red pan-S, Black pan-N)
YES
    Is the voltage moving 
alternately between Positive and 
negative?
 Check the outdoor wiring connection.
Is it normal?
Check the reactor.
YES
Is it normal?
Replace the outdoor PCB.
Power on.
YES
Is the error 
resolved?
Replace  the indoor  PCB.
NO
Replace  the 
reactor
NO
Check the indoor wiring 
connections
Is it normal?
Replace the indoor PCB.
Power on.
YES
Is the error resolved?
Replace  the outdoor  PCB.
NO
The voltage moves alternately with 
positive value.
NO
The voltage is a 
certain value
NO