Midea MHC-96HWD1N1(A) Service Manual page 44

R410A Full DC Inverter Split Duct Type Technical Manual

H8: High pressure sensor error
When the discharge pressure is lower than 0.3MPa, the system will display H8 error, the ODU in standby. When the
discharge pressure is back to normal, H8 disappears and normal operation resumes.
H8: High pressure sensor error
High pressure sensor connection
port on main control board is loose
No
High pressure sensor is
short circuit or disabled①
No
System is lack of refrigerant②.
(Refrigerant recharging is not
according to the requirement,
or there has refrigerant
leakage)
No
The low pressure side is blocked③
for squashed pipe, closed EXV,
closed strop valve, dirty filter, etc.
No
The heat exchange of evaporator
is not good. It may be caused by
dirty heat changer, abnormal IDU
fan running, some barrier in front
of the air outlet, etc.
No
Outdoor main control
board is damaged
Note:
How to check whether the high pressure sensor is short circuit or disabled①
Measure the resistance among the three terminals of the pressure sensor, if the resistance value is megohm or infinite, the
pressure sensor is disabled, otherwise, it may be normal.
2. The phenomenon of lack of refrigerant②:
Top temperature and discharge temperature of all compressors are higher than normal value, discharge pressure and
suction pressure are both lower than normal value, current is lower than normal value, suction pipe may be frosting. All the
phenomenon will disappear after recharging refrigerant.
3. The phenomenon of the low pressure side is blocked③:
The discharge temperature is higher than normal value*, low pressure is lower than normal value*, current is lower than
normal value* and suction pipe may be frosting.
43
Yes
Fasten the connection port
Yes
Replace the sensor
Yes Add refrigerant or check up
the leakage of the system
Make sure all valves are open, clean
Yes
the filter, if the filter is blocked by ice,
the system should be clean
Yes
Check the system and
fixed up the error
MCAC-UTSM-201503
Replace the outdoor
main control board