GREE U-Match 5 SERIES UNIT SERVICE MANUAL
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2.2.1.3 Outdoor Fan Control
This series air conditioner has two types of outdoor units: one with a single fan and the other with double fans. The outdoor fan
can run at the highest level 10 and the lowest level 1. By controlling the speed of outdoor fan, the unit can achieve cooling at low
temperature and heating at high temperature. In fan mode, outdoor fan will not work.
2.2.1.4 .4-way Valve Control
After heating mode is turned on for a while, 4-way valve will be energized to change the direction of refrigerant flow so that the
system can run in heating and the indoor unit will not blow cold air. Under other modes, the valve will not be energized.
To avoid the 4-way valve from incorrectly changing directions, when the unit stops in heating, due to a temperature point or
other protection reasons, the 4-way valve will continue to function temporarily and lose power after a while.
There must be adequate differential pressure for the 4-way valve to change directions.
2.2.2 Special Control
2.2.2.1 Defrosting Control
ODU defrosting control in heating: Defrosting will start when the temperature sensed by outdoor tube temperature sensor
reaches a preset value. During defrosting, the 4-way valve will switch to the cooling condition, and outdoor and indoor fans will both
stop. When the temperature sensed by outdoor tube temperature sensor reaches the preset value of defrosting stop, system will
quit defrosting. The 4-way valve will switch back to the heating condition, outdoor fan will start working first and indoor fan will
resume its previous fan speed after performing cold air prevention.
2.2.2.2 Oil Return Control
If the unit is running at low frequency for a long time, system will enable oil return control. This is to lead oil in the pipeline back
to the compressor so that the compressor will not be lack of oil. Generally, the oil return takes about 5min. The compressor running
frequency will be raised to the preset oil return frequency.
2.2.2.3 Refrigerant Recovery Control
Enabling method: Remote control and wired control both use the same enabling method. That is, within 5min after power is
connected, start cooling mode (turn on the unit) and set temperature at 16
℃
, then press
“▲
,
▼
,
▲
,
▼
,
▲
,
▼”
(6 times of
pressing) in 5s to enter the refrigerant recovery mode. If it is successfully enabled, the indoor unit will display the corresponding
code E3.
After the refrigerant recovery mode is enabled, if remote control or wired control sends a signal or the refrigerant recovery
mode has been enabled for 10min, system will exit from refrigerant recovery. If outdoor unit is shut down because of malfunction,
refrigerant recovery will be stopped immediately.
Please note that refrigerant recovery mode cannot be enabled under the following conditions:
1. If temperature is shielded remotely, refrigerant recovery mode cannot be enabled. You need to first unlock the remote shield
against temperature.
2. If temperature is higher than 16 degrees under energy-saving mode, refrigerant recovery mode cannot be enabled. You
need to first turn off the energy-saving mode.
2.2.2.4 Forced Operation Control
This control is used to quickly check whether the unit can operate normally after installation. Wired control has to be used to
enable this control. For cassette type unit, you can enable the control through the light board.
Enabling method through the light board of cassette type unit: After the unit is installed and connected to power, press TEST
button on the light board to enter forced operation mode. Short-press TEST button (less than 2s), cooling mode will be activated.
Long-press TEST button (more than 2s), heating mode will be activated.
Enabling method through wired control:
Under power-on status,
Forced cooling: press the
“▼”
button continuously for 5s to enter the forced test mode;
Forced heating: press the
“▲”
button continuously for 5s to enter the forced test mode.