Service Manual
26
Technical Information
fan motor operates at low speed.
◆
 When Tamb.
<
Tset-2
℃
, the compressor and the ODU fan motor stop, while the IDU fan motor runs at low speed.
In drying mode, the 4-way valve is de-energized (4-way valve is not available for cooling only unit); Temperature setting range is 
16
~
30
℃
. Fan speed can’t be adjusted.
②
Protection functions (See function protection of this section)
(4)Heating mode(heating mode is not available for cooling only uni)
① 
Operation condition and process
◆
 When Tamb.≤Tset-1
℃
, the system starts heating operation. In this case, the 4-way valve is energized. The compressor and the 
ODU fan motor operates simultaneously; The IDU fan motor will be started up after delayed for a period of time to make sure the air 
conditioner won’t blow out cold wind.
◆
 When Tpreset-1
℃<
Tamb.
<
Tpreset+1
℃
, the system keeps previous operation status. 
◆
 When Tamb.≥Tpreset+1
℃
, the compressor and the ODU fan motor stop. The 4-way valve is energized all the time. The IDU fan 
motor will blow residual heat after operating at set speed for a period of time consecutively to make sure the inner temperature of air 
conditioner won’t be too high. 
In heating mode, 4-way valve is energized. Temperature setting range is 16
~
30
℃
.
②
 Defrosting condition and process
In order to ensure heating effect, the unit will proceed defrosting automatically according to the frost situation of outdoor unit. Dual-8 
nixie tube displays H1 during defrosting. (For some models, heating icon is bright for a period of time and then OFF).
③
Protection functions (See function protection of this section)
 (5) Fan mode
①
 Operation condition and process 
The IDU fan motor operates at set speed, while the compressor, the ODU fan motor and 4-way valve stop.
②
Protection functions (See function protection of this section)
10S