Product Features
 Page 75 
1.  Operation Modes and Functions
1.1  Abbreviation
Unit element abbreviations
Abbreviation Element
T1 Indoor room temperature
T2 Coil temperature of evaporator
T3 Coil temperature of condenser
T4 Outdoor ambient temperature
T5 Compressor discharge temperature
1.2  Safety Features
Compressor three-minute delay at restart 
Compressor functions are delayed for up to one minute 
upon the first startup of the unit, and are delayed for up  
to three minutes upon subsequent unit restarts.
Low Pressure Check Function(For 36K~55K)
The low pressure switch should be always closed. If it is 
open, the system will stop until the fault is cleared. During 
defrosting procedure , 4 minutes after defrosting ends and 
5 minutes after compressor is on in heating mode, low 
pressure switch won’t be checked.
Note: The system will not check if the protection could be 
cleared in 30 seconds after the protection occurs. If this 
protection occurs 3 times, it won’t recover automatically 
until the main power is cut off.
Over-current protection
When compressor is running, if the current is over twice 
of the rated for 3 seconds, the compressor will stop and 
an error code will be displayed on the outdoor PCB. If the 
current becomes normal, the indoor sends  signal to the 
outdoor, the outdoor will display normally.
Open Circuit/Disconnection Sensor Protection 
Fan Speed Malfunction
If a fault occurs on the air volume regulator or the 
regulator enters protection mode, it sends the error 
message CF and an instruction to reduce fan speed to the 
master. The message and the instruction can be inquired 
with the remote controller or the wired controller. (Fault 
and protection information are displayed for one minute). 
After a fault occurs, the master unit shows the error code 
E3 and the fault count for one minute.
If the fault occurs three times, then the fan is unable to 
resolve the problem independently. External shutdown by 
a remote controller, wired controller, or central controller 
must be used to clear the fan fault and fault count. The 
fan runs normally for 5 minutes while clearing fault count.
1.3  Display Function
Unit display functions
MANUAL TIMER
ALARM
OPERATION
DEF./FAN
MANUAL TIMER
ALARM
OPERATION
DEF./FAN
MANUAL TIMER
ALARM
OPERATION
DEF./FAN
1.4  Fan
When fan mode is activated:
• The outdoor fan and compressor are stopped.
• Temperature control is disabled and no temperature 
setting is displayed.
• The indoor fan speed can be set to high, medium, low, 
or auto.
• The louver operations are identical to those in cooling 
mode.
1.5  Cooling Mode
1.5.1  Compressor Control
• When T1-Ts-∆T is lower than setting value, the 
compressor ceases operation.
• When T1-Ts-∆T is higher than setting value, the 
compressor continues operation.
1.5.2  Indoor Fan Control
• In cooling mode, the indoor fan operates continuously. 
The fan speed can be set to high, medium, low or auto.
• The auto fan acts according to the value of T1-TS.
1.5.3  Outdoor Fan Control
• The outdoor fan is controlled by T4 and compressor 
frequency.
1.5.4  Evaporator Temperature Protection
When evaporator temperature drops below a configured 
value for some time, the compressor ceases operation, the 
outdoor fan motor ceases operation 30 seconds later.