7) High 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
no
re-wiring
yes
Is compressor current more than overcurrent
protection limit? Is current detecting circuit in
good condition?
Confirm detecting circuit
is abnormal,replace
outdoor PCB
no
yes
yes
replace AC contactor
yes
if compressor is normal
no
Is resistance of compressor
winding incorrect? Is it stuck?
yes
replace compressor
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?
Is power cable or compressor wire
securely connected? Properly?
Modify power supply circuit
yes
Is AC contactor in
poor contact?
Short connect that
terminal
if failure disappear after
PCB is changed
yes
no
replace PCB
yes
Solve problem
accordingly
yes
Is an external alarm
connected to the system?
8) External alarm
no
Is ALARM terminal in
mainboard disconnected?
An external alarm is
identified according to the
list of fault codes
Commercial Air Conditioner Model: AP*****EAA AU*****EAA
35
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