Midea MCH2U-18PHH2, Service Manual

Page: 67 / 131

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8.4.2.5 E5 (Over-voltage or under-voltage protection) diagnosis and solution.
Error Code E5
Malfunction conditions
An abnormal voltage rise or drop is detected by checking the
specified voltage detection circuit.
Potential causes ●
Power supply problems.
●
System leakage or block
●
Faulty PCB
Trouble shooting:
Voltage protection
Check the voltage of
outdoor unit power supply,
whether the voltage
between L(L1) and N (L2) is
about 187~264VAC
Check the power supply
Check whether the voltage of IPM
board P and N(GND) is normal?
DC277—356V for 2-zone(18K Btu/h)/3
zone(27K Btu/h)
DC277-410V For 4-zone(36K Btu/h)/5-
zone(48K Btu/h)
Replace bridge rectifiers,
and then check whether the
system can run normally
(for
5-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