Product Features
 Page 83 
2.  Operation Modes and Functions 
2.1 Abbreviation
Unit element abbreviations
Abbreviation Element
T1 Indoor room temperature
T2
Coil temperature of evaporator 
middle
T2B
Coil temperature of evaporator 
outlet(It is located in outdoor unit)
T3 Coil temperature of condenser
T4 Outdoor ambient temperature
T5 Compressor discharge temperature
TS Setting temperature
2.2  Safety Features
Open Circuit/Disconnection Sensor Protection 
Automatic shutoff based on fan speed
For A6 Duct type, 
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.
For other types,
If the indoor fan speed registers below 300RPM for an 
extended period of time, it shuts off and restarts in 30 
seconds. If this happens 3 times, the unit ceases operation 
and the corresponding error code is displayed on the 
indoor unit. 
If outdoor fan speed registers below 100RPM or higher 
than 2400RPM for an extended period of time, the unit 
ceases operation and the corresponding error code is 
displayed on the indoor unit and outdoor unit.
Indoor fan delayed operation
• When the unit starts, the louver is automatically 
activated and the indoor fan will operate after a period 
of 7 seconds. 
•  If the unit is in heating mode, the indoor fan is 
regulated by the anti-cold wind function.
Zero crossing detection error protection(For Forest 
series)
If AC can not detect zero crossing signal for 4 minutes or 
the zero crossing signal time interval is not correct, the unit 
will stop and the LED will display the failure. The correct 
zero crossing signal time interval should be between 
6-13ms.
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.
Inverter module protection
The inverter module has an automatic shutoff mechanism 
based on the unit’s current, voltage, and temperature. 
If automatic shutoff is initiated, the corresponding error 
code is displayed on the indoor unit and the unit ceases 
operation.
Automatic shutoff based on discharge temperature
If the compressor discharge temperature exceeds a certain 
level for a period of time, the compressor ceases operation.
Oil return
Running rules:
1. If the compressor frequency keeps lower than setting 
frequency for setting time, the AC will rise the frequency 
to setting frequency for setting time and then resume to 
former frequency. 
2. The EXV will keep 300p while the indoor units will keep 
the current running mode.
If the outdoor ambient is higher than setting frequency 
during the oil return, the AC quit oil return.