75
Installation and Maintenance
Service Manual
(7) Communication malfunction: (following AP1 for outdoor unit control board)
Mainly detect:
●Is there any damage for the indoor unit mainboard communication circuit? Is communication circuit damaged?
●Detect the indoor and outdoor units connection wire and indoor and outdoor units inside wiring is connect well or not, if is there any
damage?
Fault diagnosis process:
Yes
No
Yes
No
No
Yes
No
No
Yes
No
Yes
No
Yes
Yes
Start
Did the equipment operate
normally before the failure
occurs?
The AP1 voltage
detection circuit
is at fault
Check wiring inside of
the indoor and outdoor
units
Are wires broken?
Check the communication
circuit of the outdoor unit
If the fault is eliminated?
The communication
circuit is abnormal
Replace the main board
of the indoor unit
End
If the fault is eliminated?
Replace the main board
AP1 of the outdoor unit
If the fault is eliminated?
Is the connection right?
Check the wiring of the indoor and
outdoor units with reference to the
wiring diagram
Correctly connect the
corresponding wires for
the indoor and outdoor
units with reference to
the wiring diagram
