Service Manual

 Troubleshooting 19 
7.2 E1 (Indoor and outdoor unit communication error diagnosis and solution)
Description: Indoor unit can not communicate with outdoor unit
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
Note: For certain models, outdoor PCB could not be removed separately. In this case, the outdoor electric
control box should be replaced as a whole.