Carrier 38MGRBQ18B-3 - DIAGNOSIS AND SOLUTION (CONT); Over-Voltage or Under-Voltage Protection

38MGRBQ: Service Manual
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DIAGNOSIS AND SOLUTION (CONT)
Over-voltage or under-voltage protection diagnosis and solution
Troubleshooting
ERROR CODE
E5, PC 10, PC 11 OR PC 12
MALFUNCTION DECISION
CONDITIONS
When the supply voltage to the unit or to the main control board is outside the acceptable tolerance, the unit’s
LED displays E5, PC 10, PC 11 or PC 12 and then the unit turns off.
SUPPOSED CAUSES
Issues with supply voltage
Wiring mistake
IPM malfunction
Faulty outdoor PCB
Voltage protection
Check the voltage of
outdoor unit power supply,
whether the voltage
between L(L1) and N (L2) is
about 187~253VAC
Check the power supply
Check whether the voltage
of IPM board P and N is
normal: DC277-356V for
18-27KBtu/h; DC277-410V
for 36KBtu/h
Replace bridge rectifiers
and then check whether the
system can run normally
(Only for qua-zone).
Replace IPM board, and
then check whether the
system can run normally
Replace outdoor main board
Yes
No
No
No
No
Yes
Trouble is solved
Yes
Yes