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Technical Information
Service Manual
6. Function and Control
1 Basic functions of the system
1.1 Cooling Mode
1.1.1 Cooling conditions and process:
If the compressor is in stop status and start the unit for cooling
operation, when one of the indoor units reaches the cooling
operation condition, the unit start cooling operation; in this
case, the electronic expansion valve, the outdoor fan and the
compressor start operation.
1.1.2 Stop in cooling operation
1.1.2.1 Compressor stops
The compressor stops immediately, the outdoor fan stops after
1min.
1.1.2.2 Some of the indoor units reach the stop condition (the
compressor does not stop)
The compressor operates immediately according to the
required frequency. For the indoor unit with no requirement, the
corresponding electronic expansion valve is closed to OP.
1.1.3 Cooling mode transfers to heating mode
When the unit transfers to heating mode, the 4-way valve
is energized after the compressor stops for 2min. The other
disposals are the same as stopping in cooling mode.
1.1.4 4-way valve: in this mode, the 4-way valve is closed.
1.1.5 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 for 3min after starting and
then it will run in set speed. The fan shall run at every speed for
at least 80s. (When the quantity of running indoor unit is changed,
the unit will enter the control described in 1.3.5.1 and 1.3.5.2);
When the compressor stops, the outdoor fan runs at present
speed and stops after 1min.
1.2 Dry Mode
1.2.1 The dry conditions and process are the same as those in
cooling mode;
1.2.2 The status of 4-way valve: closed;
1.2.3 The temperature setting range: 16 ~ 30
o
C;
1.2.4 Protection function: the same as those in cooling mode;
1.2.5 In dry mode, the maximum value A of the capacity
requirement percentage o f single unit is 90% of that in cooling
mode.
The open condition of the electronic expansion valve, outdoor fan
and compressor is the same as those in cooling mode.
1.3 Heating Mode
1.3.1 Heating conditions and process:
When one of the indoor units reaches the heating operation
condition, the unit starts heating operation.
1.3.2 Stop in heating operation:
1.3.2.1 When all the indoor units reach the stop condition, the
compressor stops and the outdoor fan stops after 1min;
1.3.2.2 Some of the indoor units reach the stop condition
The compressor reduces the frequency immediately and operates
according to the required frequency;
1.3.2.3 Heating mode transfers to cooling mode(dry mode), fan
mode
a. The compressor stops; b. the power of 4-way valve is cut off
after 2min; c. the outdoor fan stops after 1min; d. the status of
4-way valve: energized;
1.3.3 Outdoor fan control in heating mode
The outdoor fan starts before 5s of the starting of compressor
and then it will run in high speed for 40s;
The fan shall run at every speed for at least 80s;
When the compressor stops, the outdoor fan stops after 1min.
1.3.4 Defrosting function
When the defrosting condition is met, the compressor stops;
the electronic expansion valve of all indoor units open in big
angle; the outdoor fan stops after 40s of the stop of compressor,
meanwhile, the 4-way valve reverses the direction; after the 4-way
valve reverses the direction, the compressor starts; then begin to
calculate the time of defrosting, the frequency of the compressor
rises to reach the defrosting frequency.
1.3.5 Oil-returned control in heating mode
1.3.5.1 Oil-returned condition
The whole unit is operating in low frequency for a long time.
1.3.5.2 Oil-returned process in heating mode
The indoor unit displays “H1”.
1.3.5.3 Oil-returned finished condition in heating mode
The duration reaches 5min.
1.4 Fan Mode
The compressor, the outdoor fan and the 4-way valve are closed;
temperature setting range is 16 ~ 30
o
C.
2 Protection Function
2.1 Mode Conflict Protection of indoor unit
When the setting mode is different of different indoor unit, the unit
runs in below status:
a. The mode of the first operating indoor unit is the basic mode,
then compare the mode of the other indoor units to see if there
is a conflict. Cooling mode (dry mode) is in conflict with heating
