35
(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.
Released
Cold Air Prevention
18
:
22
:
Fan speed
Set speed
Very Low or stop
3. 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 (MUCFH-13NV-
,MUCFH-24NV-
), 50°C (MUCFH-18NV-
), 56°C(MUCFH-18NV-
)
Outdoor fan ON : 48°C (MUCFH-13NV-
,MUCFH-24NV-
), 46°C (MUCFH-18NV-
), 52°C(MUCFH-18NV-
)
E4
E3
E3
E4
E4
E3
E3
E4
High pressure protection
Released
48
:
46
:
52
:
52
:
(MUCFH-13NV- ,MUCFH-24NV- )
50
:
(MUCFH-18NV- )
56
:
(MUCFH-18NV- )
ON
Outdoor fan
OFF
E4
E3
E3
E4
High pressure protection chart
Example
Indoor coil thermistor
RT12 temperature
MUCFH-13NV-
: 52˚C
MUCFH-24NV-
: 52˚C
MUCFH-18NV-
: 50˚C
MUCFH-18NV-
: 56˚C
E4
E3
E3
E4
Outdoor fan motor
turn OFF
Outdoor fan motor
turn ON
Outdoor fan motor
ON
ON
OFF
OFF
NOTE1. : • When the outdoor fan is OFF in heating, defrosting of outdoor heat exchanger is not detected by the defrost ther-
mistor RT61.
MUCFH-13NV-
: 48˚C
MUCFH-24NV-
: 48˚C
MUCFH-18NV-
: 46˚C
MUCFH-18NV-
: 52˚C
E4
E3
E3
E4
2. Outdoor fan control <MUCFH-24NV -
>
Outdoor fan speed is controlled according to the temperature of ambient temperature thermistor RT63.
Outdoor fan Low operation : Until when the outside temperature decreases to 12°C.
When the outside temperature goes to 14°C or more.
Outdoor fan High operation : When the outside temperature decreases to 12°C or less.
Until when the outside temperature goes to 14°C.
E3
Outdoor fan speed
12
:
14
:
High
Ambient temperature
thermistor RT63 temperature
Low
NOTE2. : • Refer to service manual OB185 REVISED EDITION-C for MCFH-13NV-
or MCFH-18NV-
is connected
with MXZ-32NV-
.
• Refer to service manual OB227 REVISED EDITION-B for MCFH-13NV-
or MCFH-18NV-
is connected
with MXZ-32RV-
.
• Refer to service manual OB254 for MCFH-13NV-
or MCFH-18NV-
is connected with MXZ-32SV-
.
E1
E3
E4
E1
E3
E4
E2
E3
E4
OB267--2.qxp 01.12.19 3:00 PM Page 35
