Cooling Mode; Dry Mode; Heating Mode - Gree GWHD(18)NK3FO Service Manual

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
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 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.

1.3 Heating Mode

1.3.1 Cooling 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;
;