Haier HBU-18HF03 Manual page 249

6) Communication failure between wired controller and indoor PCB 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
7) Over current protection in 3-phase fixed frequency models
Is three-phase circuit not balanced? Is
supply voltage too low? Is supply
voltage too low at compressor start-up?
yes
Is power cable or compressor wire
securely connected? Properly?
yes
Is compressor current more than overcurrent protection
limit? Is current detecting circuit in good condition?
yes
Is AC contactor in poor contact?
yes
if compressor is normal
yes
if pressure is normal
no
Check: 1. Is a valve in system shut off;
2. Is piping clogged;
3. Is system overfed; is there air in system;
4. (Cooling cycle) Is condenser dirty? Does outdoor fan motor run at low speed or stop?
5. (Heating cycle) Is evaporator or filter dirty? Does indoor fan motor run at low speed or stop?
6. Is ambient temperature too high? Is system overloaded?
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
yes
Modify power supply circuit
no
re-wiring
no
yes
replace AC contactor
no
Is resistance of compressor
winding incorrect? Is it stuck?
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check if the dip
yes
yes
switch position on
PCB is right
no
correct the position
Confirm detecting circuit
is abnormal,replace
outdoor PCB
yes
replace compressor
Troubleshooting
replace PCB