42
Installation and Maintenance
Service Manual
6
Zero-crossing
inspection
circuit
malfunction
of the IDU fan
motor
U8
Operation of remote controller or control
panel is available, but the unit won’t act.
1.Quick de-energization and energization. Wrong
judgement by the controller because the electric-
discharging of capacitor is slow.
2.Zero-crossing inspection circuit of main board for
controller is abnormal.
7
Lack of
refrigerant
or block
protection for
the system(not
applicable to
residential air
conditioner)
or Overload
protection
compressor
F0
The Dual-8 Code Display will show F0
and the complete unit stops.
1.Refrigerant leakage;
2.Indoor evaporator temperature sensor works abnormally;
3.The unit has been plugged up somewhere;
4.The compressor can’t be started up normally. Because
the power voltage for the complete unit is too low, and the
outdoor working condition is too high.
8
Overcurrent
protection
E5
Cool/Dry: compressor and outdoor
fan stops operation, while indoor fan
operates;
Heat: all loads stops operation.
1.Power voltage is unstable;
2.Power voltage is too low;
3.System load is too high, which leads to high current;
4.Heat exchange of indoor unit is too dirty, or it blocked the
air inlet/outlet;
5.Fan motor operation is abnormal; the fan speed is too
low or not functioning;
6.Compressor is blocked;
7.The internal system is blocked; (dirt blockage, ice
blockage, oil blockage, angle valve is not completely
opened)
8.Main board of outdoor unit is damaged.
9
High pressure
protection of
system
E1
1.Heat exchange of outdoor unit is too dirty, or it blocked
the air inlet/outlet;
2.Ambient temperature is too high;
3.Is power voltage normal; (three-phase unit)
4.Refrigerant is too much.
5.Wiring of high pressure switch is loose or high pressure
switch is damaged;
6.The internal system is blocked; (dirt blockage, ice
blockage, oil blockage, angle valve is not completely
opened)
10
Overload
protection for
compressor
H3
The entire unit stops.
1. Outdoor and indoor heat exchangers are too dirty or the
air inlet/outlet is blocked.
2. Fan motor is not working Abnormal fan speed; fan
speed is too low or the fan doesn't run.
3. Compressor doesn't work normally.Strange noise or
leakage occurs.Temperature of the shell is too high.
4. System is blocked inside(dirt block, ice block, oil block,
Y-valve not fully open).
5. High pressure switch is abnormal.
6. The refrigerant is leaking and cause overheating
protection to compressor.
