Service Manual
25
Installation and Maintenance
6.3 Introduction of Each Mode Function
1.Summary
 Temperature parameter
 
◆
Indoor set temperature (Tpreset)
 
◆
Indoor ambient temperature (Tamb.)
 
◆
Inner tube temperature of indoor evaporator (Ttube)
2. Introduction of basic mode function
Once the compressor is energized, there should be a minimum interval of 3 mins between two start-ups.
If the unit is with memory function and is off before power failure, the compressor can be restarted without an interval of 3 mins; if the 
unit is on before power failure, the compressor will be restarted with an interval of 3 mins.
Once compressor is started, it won’t stop within 6 mins according to the change of room temp.
(1) Auto mode
①
 Operation condition and process
Under auto mode, the system will automatically select operation mode (cooling, dry, heating and fan) according to indoor ambient 
temperature.
◆
 When Tamb.
>
26
℃
, the system operates under cooling mode; Ex-factory set temperature is 26
℃
.
◆
 When 20
℃
≤Tamb.≤26
℃
, the system operates under drying mode; Ex-factory set temperature is 24
℃
.
◆
 Heat pump unit: when Tamb.
<
20
℃
, the system operates under heating mode; Ex-factory set temperature is 20
℃
.
◆
 Cooling only unit: when Tamb.
<
20
℃
, the system operates under fan mode; Ex-factory set temperature is 20
℃
.
②
 Protection function is same as that under cooling, drying and heating mode. (See function protection of this section)
(2) Cooling mode
①
Operation condition and process
◆
 When Tamb.≥Tset+1
℃
, the system operates under cooling mode. In this case, the compressor and the ODU fan motor operate, 
and the IDU fan motor operates at set speed.
◆
 When Tset-1
℃<
Tamb.
<
Tset+1
℃
, the system will maintain its previous operation status.
◆
 When Tamb.≤Tset-1
℃
, the compressor and the ODU fan motor stop, while the IDU fan motor operates at set speed.
In cooling mode, the 4-way valve is de-energized (4-way valve is not available for cooling only unit). Temperature setting range is 
16
~
30
℃
. 
 
Indicates operation
Indicates stop
Tpreset +1 ˚C
Tpreset –1 ˚C
Compressor 
Outdoor fan motor 
Indoor fan motor
Graphic instruction: 
(Same as below)
Tamb.
Stop cooling 
Start cooling 
 
②
 Protection function (See function protection of this section)
(3) Drying mode
①
Operation condition and process
◆
 When Tamb.
>
Tset+2
℃
, the system starts drying and cooling. In this case, the compressor and the ODU fan motor operate, and 
the IDU fan motor operates at low speed. 
◆
 When Tset-2
℃
≤Tamb.≤Tset+2
℃
, the compressor and the ODU fan motor operate for 6 mins and stop for 4 mins in cycle; the IDU