2HUM18HC03/R2(DB)-SM  Wiring diagrams 
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Domestic air conditioner
5.Funcitions and Control 
5.1 Main functions and control specification of indoor unit
5.1.1  Automatic operation 
When the system is under the automatic operation option, the appropriate operation mode will be 
decided according to the differences between the preset temperature and the indoor temperature 
after the system starts up. Then, the system will operate according to the chosen mode. In the 
following conditions, Tr stands for indoor temperature and Ts stands for outdoor temperature. 
The system will choose the operation mode according to the following conditions when entering 
into the automatic operation option for the first time. 
TrıTs-3ć Choose the cooling mode 
Tr˘Ts-3ć Choose the warming mode 
Under the automatic option, the system will switch between the cooling and warming modes 
according to the change of the indoor temperature. If the air conditionic is under the cooling 
mode, when the preset temperature for stopping the compressor is reached, the compressor will 
be stopped. The indoor temperature will be tested again 15 minutes after the stop of the 
compressor. At the moment, if the tested temperature is under the Tr˘Ts -3ć condition, the 
system will be switched into the warming mode. If not, the system will remain in the cooling mode. 
If the air conditionic is under the warming mode, when the preset temperature for stopping the 
compressor is reached, the compressor will be stopped. The indoor temperature will be tested 
again 15 minutes after the stop of the compressor. At the moment, if the tested temperature is 
under the Tr˚Ts +3ć condition, the system will be switched into the cooling mode. If not, the 
system will remain in the warming mode. 
5.1.2  Cooling operation mode 
Temperature control range:    16ć---30ć
Temperature difference: r1ć
* Control features: When Tr˄input airflow˅>Ts˄set temperature˅ć, the compressor will be 
opened,the indoor fan will operate at the set speed and the mode signal will be sent to the 
outdoor system. When Tr˄input airflow˅ Ts˄set temperature˅ć, the compressor will be 
opened,the indoor fan will operate at the set speed and the mode signal will be sent to the 
outdoor system. The system will keep the original status if Tr= Ts. 
Airflow speed control: (temperature difference 1ć)
Automatic: When Tr>=Ts+3ć, high speed. 
          When Ts+1ć=<Tr<Ts+3ć, medium speed 
          When Tr<Ts+1ć, low speed 
          When the sensor is off, low speed 
When the airflow speed has no delay from the high to low switching, the speed should be 
delayed for 3 minutes (remain at high speed for 3 minutes.) before the next switch.