Lennox LI009HI-230P432, Service Manual

Page: 97 / 156

94
Installation and Maintenance
Service Manual
8.Communication malfunction (AP1 below is control board of outdoor unit)
Main detection point:
● Check if the connection wire and the built-in wiring of indoor and outdoor unit is connected well and no damaged;
● If the communication circuit of indoor mainboard is damaged? If the communication circuit of outdoor mainboard (AP1) is dam
-
aged
Malfunction diagnosis process:
Start
Check communication
circuit of outdoor unit
Problem of
communication
circuit
Check built-
in wiring of
indoor and
outdoor unit
Connection
correct?
Malfunction of
circuit is
detected with
control board
AP1 voltage
Check connection
wire of indoor and
outdoor unit with
circuit diagram
Check connection
wire of indoor and
outdoor unit with
circuit diagram
If the unit is operation
normal before malfunction
Y
N
Y
N
If the wiring is
damaged?
If the malfunction
is removed?
N
Y
N
If the malfunction
is removed?
N
Replace indoor
board
Replace outdoor
mainboard AP11
If the
malfunction is
removed?
Y
N
Y
N
Y
Y
End