38
(2) Cold air prevention control
1
When the compressor is not operating,
(
1
) if the temperature of indoor coil thermistor RT12 is 18°C or less, the fan stops.
(
2
) if the temperature of indoor coil thermistor RT12 is more than 18°C, the fan operates at Very Low.
2
When the compressor is operating,
(
1
) if the temperature of RT12 is 22°C or more, the fan operates at set speed.
(
2
) if the temperature of RT12 is less than 22°C and
(
1
) if the temperature of room temperature thermistor RT11 is 15°C or less, the fan stops.
(
2
) if the temperature of room temperature thermistor RT11 is more than 15°C, the fan operates at Very Low.
Indoor coil thermistor
RT12 temperature
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 the following any condition of
1
(a. ~ d.) and the condition of
2
are satisfied at the same time, warm air control
works.
1
a.) when the operation mode has been changed to HEAT mode
b.) when cold air prevention has been released
c.) when defrosting has been finished
d.) when the compressor starts in HEAT mode
2
When the temperature of indoor coil thermistor RT12 is less than 37°C.
When warm air control works, the fan speed changes as follows to blow out warm air gradually.
Gradation of fan speed in initial
The upper limit of the fan speed in MANUAL is the set speed.
The upper limit of the fan speed in AUTO is the speed decided by indoor fan speed control.
(Refer to 9-4.1. Indoor fan speed control (1).)
When the temperature of RT12 has been 37°C or more, or when the set speed has been changed, this control is
released and the fan speed is the set speed.
(4) Flow soft control
When the thermostat (compressor) is off, the indoor fan operates as follows.
RT12
fan
less than 18°C
off
18°C or more
Very Low
Released
Cold Air Prevention
18
:
22
:
Fan speed
Set speed
Very Low or stop
<Time condition>
<Indoor fan speed>
less than 2 minutes
Low
2 minutes to 4 minutes
Med.
more than 4 minutes High
NOTE : When the thermostat(compressor) turns on, the fan will operate
at set speed. But until cold air prevention and warm air control
is released, the fan speed follow them.
NOTE : During high pressure protection and for 4 min. and 15 sec. after high pressure protection, defrosting of outdoor heat
exchanger is not detected by the defrost thermistor RT61.(Refer to 9-4.3. Defrosting)
(MUH-C07/C09TV)52˚C
(MUH-C12TV)56˚C
(MUH-C07/C09TV)48˚C
(MUH-C12TV)52˚C
Outdoor fan motor
Outdoor fan motor
turn OFF
Outdoor fan motor
turn ON
ON
ON
OFF
OFF
2. High pressure protection
During heating operation, the outdoor fan motor is controlled by the temperature of indoor coil thermistor RT12 for excess
rise protection of compressor discharge pressure.
Outdoor fan OFF: 52
:
(MUH-C07/C09TV)
56
:
(MUH-C12TV)
Outdoor fan ON: 48
:
(MUH-C07/C09TV)
52
:
(MUH-C12TV)
Operation chart
Example
Indoor coil thermistor
RT12 temperature
High pressure protection
Released
48
:
52
:
52
:
(MUH-C07/C09TV)
56
:
(MUH-C12TV)
Outdoor fan
OFF
ON
Indoor coil thermistor
RT12 temperature
