Haier HPU-42CV03 Service Manual page 51

4) Communication error between indoor and outdoor units
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
5) Phase loss or phase failure
confirm the malfunction
according to the fault code list
Check if the phase detecting
circuit is correct according to
ourdoor wiring diagram
yes
Is there phase loss
or phase failure?
no
Is fault corrected after
sequence of either two of three
RST phases is adjusted?
no
replace outdoor
PCB
Commercial Air Conditioner
yes
yes
yes
S should not share
a multicore cable
with L and N
if the failure disappear
no
after correcting the
wiring
no
adjust power
supply
Are communication wire
no
P, Q connected contrarily
and supply wires L and N
properly connected?
yes
if communication wire
is broken
no
check if indoor/outdoor PCB fuse
and transformer are normal
yes
replace indoor PCB
if failure is eliminated
no
50
Model: HPU-42CV03
HPU-42HV03
no
re-wiring
yes
re-wiring
change
no
defective parts
no
replace outdoor PCB