Service manual

2 MAIN LOGIC
2�1 Control Function of Outdoor Unit
2.1.1 Cooling Mode
a. 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.
b. Stop in cooling operation
a) Compressor stops
The compressor stops gradually, the outdoor fan stops after 1min.
b) Some of the indoor units reach the stop condition (the compressor does not stop) The compressor operates
according to the required frequency. For the indoor unit with no requirement, the corresponding electronic expansion valve
is closed to 0P.
c. Cooling mode transfers to heating mode
When the unit transfers to heating mode, the 4-way valve is energized after the compressor runs for 40s. The other
disposals are the same as stopping in cooling mode.
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 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.
2.1.2 Dry Mode
a. The dry conditions and process are the same as those in cooling mode;
b. The status of 4-way valve: closed;
c. The temperature setting range: 16 ~ 30
℃
;
d. Protection function: the same as those in cooling mode;
e. In dry mode, the maximum value A of the capacity requirement percentage of 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.
2.1.3 Heating Mode
a. Heating conditions and process: When one of the indoor units reaches the heating operation condition, the unit
starts heating operation.
b. Stop in heating operation:
a) When all the indoor units reach the stop condition, the compressor stops and the outdoor fan stops after 1min;
b) Some of the indoor units reach the stop condition The compressor reduces the frequency immediately and operates
according to the required frequency;
c) Heating mode transfers to cooling mode(dry mode), fan mode
The compressor stops;
The outdoor fan stops after 1min;
The status of 4-way valve: energized;
c. 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.
d. 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 the stop of the 4-way valve, 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.
e. Oil-returned control in heating mode
a) Oil-returned condition
The whole unit is operating in low frequency for a long time
b) Oil-returned process in heating mode
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