Haier Unitary smart series Service Manual page 183

5) Communication error between indoor and outdoor units - Wired controller shows
Confirm commumication failure
according to the fault code list
Confirm the fault indicator is
communication failure
Does indoor communication
indicator flash?
Is communication wire too
no
close to power cable, which
check the other
causes interference?
reasons
S should not share
a multicore cable
with L and N
6) Communication failure between wired controller and indoor PCB - Wired controller shows
or no display on wired controller
Confirm commumication failure
according to the fault code list
or no display
check if the wired controller
can match with indoor PCB
yes
Is power just turned on?
no
Is voltage between A and
B of wired controller 12V?
no
Is supply transformer or 7812
component in good condition?
no
check if failure disappears after
changing transformer or PCB
no
check if failure disappears after
changing wired controller
yes
no
yes
yes
check if indoor/outdoor PCB fuse
and transformer are normal
no
replace wired controller
for some models, when powered on,
yes
initialization will display 88, if initrialization
cannot finish, check indoor dip switch position
yes
Is voltage between B
and C fluctuating?
no
yes check if wiring
is correct
yes wired controller is
broken
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a__ a__
06
Are communication wire
S and supply wires L and
N properly connected?
Grounded well?
yes
if communication wire
is broken
no
yes
replace indoor PCB
no
if failure is eliminated
check if the dip
yes
switch position on
PCB is right
no
correct the position
^ ^ a` a` a` a`
no
re-wiring
yes
re-wiring
change
no
defective parts
replace outdoor PCB
07
yes
replace PCB