Mitsubishi MCFH-13NV Service Manual page 35

— HEAT mode of "I FEEL CONTROL" —
1. Indoor fan speed control
(1) In AUTO the fan speed is as follows.
Set temperature minus room temperature: 2 degrees or more ···························High
Set temperature minus room temperature: Between 1 and 2 degrees ···············Med.
Set temperature minus room temperature: less than 1 degree ···························Low
(2) Cold air prevention control
The fan runs at set speed when the indoor coil thermistor RT12 temperature exceeds 22°C. The fan operates at Very
Low when the temperature of indoor coil thermistor RT12 is below 18°C. But the fan stops when the indoor fan operates
at Very Low and the room temperature is 15°C or less.
NOTE : If the temperature of RT12 reads from 18°C to 22°C at the air conditioner starting and also after defrosting, this
control works.
(3) Warm air control
When compressor starts in heating operation or after defrosting, the fan changes the speed due to the indoor coil ther-
mistor RT12 temperature to blow out warm air.
After releasing of cold air prevention, when the indoor coil temperature is 37°C or above, the fan speed shifts to the set
speed, and when the fan speed is changed by the remote controller, the fan speed is the set speed.
When the indoor coil temperature is less than 37°C, the fan speed is controlled by time as below.
<Time condition> <Indoor fan speed>
less than 2 minutes ························Low
2 minutes to 4 minutes···················Med.
4 minutes or more ··························High
The upper limit of the fan speed is the set speed.
If the thermostat turns off, this operation changes to flow soft control.
(4) Flow soft control
After the thermostat turns off, the indoor fan operates at Very Low.
NOTE : When the thermostat turns on, the fan operates at the set speed. Due to the cold air prevention control, the fan
does not start at set speed until the indoor coil thermistor RT12 reads 22°C or more.
2. High pressure protection
During heating operation, the outdoor fan motor is controlled by the temperature of indoor coil thermistor RT12 temperature
for excess rise protection of compressor discharge pressure.
Outdoor fan OFF : 52°C (MCFH-13/24), 50°C (MCFH-18)
Outdoor fan ON : 48°C (MCFH-13/24), 46°C (MCFH-18)
High pressure protection chart
Example
Indoor coil thermistor
RT12 temperature
MCFH-13/24 : 52˚C
MCFH-18 : 50˚C
MCFH-13/24 : 48˚C
MCFH-18 : 46˚C
Outdoor fan motor
NOTE : When the outdoor fan is OFF in heating, defrosting of outdoor heat exchanger is not detected by the defrost thermistor
RT61.
Initial temperature difference
Released
Cold Air Prevention
High pressure protection
Released
ON ON
OFF
35
Fan speed
Fan speed
Set speed
Very Low or stop
18: 22:
Outdoor fan
OFF
ON
48: 52:
46: 50:
OFF
Difference between room
temperature and set temperature
during operation
2deg. 4deg.
1deg. 1.7deg.
Outdoor fan motor
turn OFF
Outdoor fan motor
turn ON