Midea Forest MOAA31-12CN1-NB8, Technical Manual

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 Page 30 

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1.2  Abbreviation

Unit element abbreviations

Abbreviation

Element

T1

Indoor room temperature

T2

Coil temperature of evaporator

T3

Coil temperature of condenser

1.3  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.

Zero crossing detection error protection

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.

Automatic shutoff based on fan speed 

If the indoor fan speed registers below 300RPM for 50s, 
the unit ceases operation and the corresponding error 
code is displayed on the indoor unit. 

Current protection

The current exceeds setting value for certain time, the 
compressor and outdoor fan will shut off.

Indoor fan delayed operation

•  When the unit starts, the louver is automatically 

activated and the indoor fan will operate after a period 
of 4 seconds. 

•  If the unit is in heating mode, the indoor fan is 

regulated by the anti-cold wind function.

Sensor redundancy and automatic shutoff

If one temperature sensor malfunctions, the air conditioner 
ceases operation.

Refrigerant leakage detection

This function is active only when cooling mode is selected. 
It will detect if the compressor is being damaged by 
refrigerant leakage or by compressor overload. This is 
measured using the coil temperature of evaporator T2 
when the compressor is in operation.

1.4  Fan Mode

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.

•  Auto fan: In fan-only mode, AC operates the same as 

auto fan in cooling mode with the temperature set at 
24°C.

1.5  Cooling Mode

1.5.1  Compressor Control

When indoor room temperature T1 is lower than setting 
value, the compressor and outdoor fan will shut off.

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.

1.5.3  Outdoor Fan Control

For on-off models, outdoor units just have one single fan 
speed. The operation of outdoor fan is consistent with the 
operation of compressor, except the following situations.

•  High temperature protection of condenser
•  Current protection

1.5.4  Evaporator Temperature Protection

When evaporator temperature drops below a configured 
value, the compressor and outdoor fan ceases operations.

1.5.5  Condenser Temperature Protection

 (for 

some models)

When condenser temperature is more than setting value, 
the compressor will stop.

1.6  Heating Mode(for heat pump models)

1.6.1  Compressor Control

When indoor room temperature T1 is higher than setting 
value the compressor and outdoor fan will shut off. 

1.6.2  Indoor Fan Control

•  When the compressor is on, the indoor fan can be 

set to high/med/low/auto. And the anti-cold wind 
function has the priority.

•  The indoor fan speed will adjust according to the value 

of T1-TS.