R410A Full DC Inverter Split Duct Type Technical Manual MCAC-UTSM-201503
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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.
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.
High pressure sensor is
short circuit or disabled①
System is lack of refrigerant②.
(Refrigerant recharging is not
according to the requirement,
or there has refrigerant
Add refrigerant or check up
the leakage of the system
The low pressure side is blocked③
for squashed pipe, closed EXV,
closed strop valve, dirty filter, etc.
Make sure all valves are open, clean
the filter, if the filter is blocked by ice,
the system should be clean
The heat exchange of evaporator
is not good. It may be caused by
dirty heat changer, abnormal IDU
fan running, some barrier in front
Check the system and
fixed up the error
H8: High pressure sensor error
High pressure sensor connection
port on main control board is loose
Fasten the connection port
Outdoor main control
board is damaged
Replace the outdoor
main control board
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