Haier HBU-18HF03 Manual page 250

8) External alarm
An external alarm is identified
according to the list of fault codes
Is an external alarm
connected to the system?
no
Is ALARM terminal in mainboard disconnected?
Short connect that terminal
yes
if failure disappear after PCB is changed
no
replace PCB
9) Overcurrent protection for single-phase fixed frequency models
Is supply voltage too low? Especially
when compressor starts up?
Is supply wire securely connected?
Is compressor current more than overcurrent protection
limit? Is current detecting circuit in good condition?
Is compressor in good condition?
yes
Is running capacitor in good condition?
yes
Is pressure 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?
yes
Solve problem accordingly
yes
yes
no
no
yes
yes
no Is resistance of compressor
winding incorrect? Is it stuck?
no
modify power supply circuit
re-wiring
Confirm detecting circuit
no
is abnormal,replace
outdoor PCB
replace running capacitor
-250-
Troubleshooting
yes
replace compressor