9
Technical Information
Service Manual
1. Function Control
1) Cooling mode
a. Turning on the unit for cooling operation, and if any one of the indoor units satisfy the cooling operation condition, the system will
start for cooling operation; and the electronic expansion valve, the outdoor fan and the compressor start operation.
b. When some of the indoor units satisfy the stop-condition while some indoor units does not satisfy the stop-condition, the
compressor does not stop, the compressor adjust the frequency according to demand. For the indoor unit with stop-condition satisfies,
the corresponding electronic expansion valve will be closed.
c. Change Cooling mode to heating mode
When change the unit to heating mode from cooling mode, the whole system will stop first. Then the system will restart in heating
mode after the compressor stops.
d. 4-way valve
In this mode, the 4-way valve is closed.
e. Outdoor fan control in cooling mode
The outdoor fan starts before 5s of the starting of compressor. The outdoor fan will run in high speed after starting and then it will run
in set speed.
2) Dry mode (dehumidification mode)
this mode is the same as cooling mode;
3) Heating mode
a. Turning on the unit for heating operation, If any one of the indoor unit satisfy the heating condition, the system will start to run in
heating mode
b. If all the indoor units satisfy the stop-condition, the compressor stops and the outdoor fan stops after 1min;
c. If only part of the indoor units satisfy the stop-condition, the compressor decrease the frequency immediately and operates
according to demand.
d. Change Heating mode to cooling mode or dehumidification mode, the whole system will stop first, then restart under the required
mode.
e. Defrosting function
When the defrosting condition is satisfied, the 4-way valve reverses the direction, the outdoor fan stop.After the 4-way valve reverses
the direction, the frequency of compressor rises, and the unit
will start defrosting under cooling cycle.
4) Fan mode
Only indoor fan run. Compressor, outdoor fan and 4-way valve are closed .
2. Protection Function
1) Mode conflict protection of indoor units
When the setting mode is different of different indoor unit, the unit runs in below status:
a. The system mode is determined by the first turning on indoor unit except indoor unit is in fan mode. Cooling mode (dry mode) is in
conflict with heating mode.
b. If the first turning on unit is fan mode, and the second turning on unit is cooling or heating mode, then the system will run in cooling
or heating mode
2) Overload protection
If the tube temperature at the high pressure side is higher than normal, the compressor frequency is restricted or decreased to normal
operation frequency.
3) High exhaust temperature protection
If the exhaust temperature is higher than protection value, the compressor stops running.
If the exhaust temperature protection continuously appears for 6 times, the compressor can’t resume running. In this case, only by
cutting off the power and then reenergize that the compressor can restart. If the running duration of the compressor is longer than
10min, the protection times will be cleared to zero time.
4) Communication malfunction
Detection of the quantity of installed indoor units: after 3min of energizing, if the outdoor unit does not receive the communication data
of certain indoor unit, the outdoor unit will judge that indoor unit is not installed. If the outdoor unit receives the communication data of
that indoor unit later, the communication malfunction will be cleared.
6. Function and Control
