Mitsubishi Electric MSC-CA20VB Quick start guide

SERVICE TECHNICAL GUIDE
CONTENTS
1. MSC MICROPROCESSOR CONTROL················6
2. MS MICROPROCESSOR CONTROL················15
3. MSH MICROPROCESSOR CONTROL··············26
4. MSZ-CA MICROPROCESSOR CONTROL········39
5. MSZ-FA MICROPROCESSOR CONTROL ········54
6. MSZ-GA, MSZ-CB
MICROPROCESSOR CONTROL ············72
7. MCF MICROPROCESSOR CONTROL············100
8. MCFH MICROPROCESSOR CONTROL·········106
9. MFZ MICROPROCESSOR CONTROL ············115
10. MSZ-HA MICROPROCESSOR CONTROL·····127
11. MSZ-GB MICROPROCESSOR CONTROL·····137
12. MXZ MICROPROCESSOR CONTROL···········150
Wireless type Models
Multi system type Models
SPLIT-TYPE, AIR CONDITIONERS
SPLIT-TYPE, HEAT PUMPAIR CONDITIONERS
FLOOR AND CEILING TYPE AIR CONDITIONERS
FLOOR TYPE, HEAT PUMPAIR CONDITIONERS
MSC-CA•VB - · MU-GA•VB -
MSC-CB•VB - · MUH-GA•VB -
MSC-GA•VB - E
EE
EE
· MXZ-A•VA - E
MCF-GA•VB - · MUCF-GA•VB -
MCFH-GA•VB - · MUCFH-GA•VB -
MFZ-KA•VA - E
EE
EE
MS-GA•VB - · MU-GA•VB -
MSH-CA•VB -
MSH-CB•VB -
MSH-GA•VB - · MUH-GA•VB -
MSZ-CA•VB - · MUZ-CA•VB -
MSZ-FA•VA - · MUZ-FA•VA -
· MUZ-FA•VAH -
MSZ-GA•VA - · MUZ-GA•VA -
· MUZ-GA•VAH -
MSZ-CB•VA -
MSZ-HA•VA - · MUZ-HA•VA -
MSZ-GB•VA - · MUZ-GB•VA -
EE
EE
E
E
EE
E
EE
EE
EE
E
E
EE
Wireless type Models
Inverter-controlled multi system type Models
· MUX-A•VB - E
Wireless type Models
No. OBT06
REVISED EDITION-D
Revision D:
• MXZ-5A100VA - has been added.
E
Please void OBT06 REVISED EDITION-C.
OBT06D--1qxp 07.3.2 9:22 AM Page 1

1. MSC MICROPROCESSOR CONTROL·························································6
Indoor unit models Outdoor unit models
MSC-CA20VB MSC-CB20VB MSC-GA20VB MU-GA20VB MUH-GA20VB MUX-2A28VB
MSC-CA25VB MSC-CB25VB MSC-GA25VB MU-GA25VB MUH-GA25VB MUX-2A59VB
MSC-CA35VB MSC-CB35VB MSC-GA35VB MU-GA35VB MUH-GA35VB MUX-3A60VB
MUX-2A70VB
MUX-3A63VB
MUX-4A73VB
1-1. COOL OPERATION················································································6
1-2. DRY OPERATION ··················································································7
1-3. FAN OPERATION···················································································8
1-4. HEAT OPERATION ················································································8
1-5.“I FEEL CONTROL” OPERATION ·························································9
1-6. INDOOR FAN MOTOR CONTROL ······················································11
1-7. AUTO VANE OPERATION ···································································11
1-8. TIMER OPERATION·············································································12
1-9. EMERGENCY / TEST OPERATION ····················································13
1- 10
. OUTDOOR UNIT ACTUATOR CONTROL··········································14
2. MS MICROPROCESSOR CONTROL ·························································15
Indoor unit models Outdoor unit models
MS-GA50VB MU-GA50VB
MS-GA60VB MU-GA60VB
MS-GA80VB MU-GA80VB
2-1. “I FEEL CONTROL” OPERATION ······················································15
2-2. COOL OPERATION··············································································18
2-3. DRY OPERATION ················································································19
2-4. FAN OPERATION·················································································19
2-5. INDOOR FAN MOTOR CONTROL······················································19
2-6. AUTO VANE OPERATION···································································19
2-7. TIMER OPERATION·············································································22
2-8. EMERGENCY / TEST OPERATION ····················································23
2-9. EXPANSION VALVE CONTROL (LEV CONTROL) ····························24
2- 10. FUNCTION OF SOFT START RELAY ·················································25
3. MSH MICROPROCESSOR CONTROL·······················································26
Indoor unit models Outdoor unit models
MSH-CA50VB MSH-GA50VB MUH-GA50VB
MSH-CB50VB MSH-GA60VB MUH-GA60VB
MSH-GA80VB MUH-GA80VB
3-1. “I FEEL CONTROL” OPERATION ······················································26
3-2. COOL OPERATION··············································································32
3-3. DRY OPERATION ················································································32
3-4. HEAT OPERATION ··············································································32
3-5. INDOOR FAN MOTOR CONTROL······················································32
3-6. AUTO VANE OPERATION···································································33
3-7. TIMER OPERATION·············································································35
3-8. EMERGENCY / TEST OPERATION ····················································36
3-9. EXPANSION VALVE CONTROL (LEV CONTROL) ····························37
3- 10. FUNCTION OF SOFT START RELAY·················································38
2
Revision A: • MFZ-KA•VA - has been added.
E
Revision B: • MSZ-CB•VA - has been added.
• MSZ-HA•VA - has been added.
• MSZ-GB•VA - has been added.
• MXZ-2A40/52VA - has been added.
E
E
E
E
Revision C: • MXZ-2A30VA - and MXZ-2A40VA - have been added.
E2E
Revision D: • MXZ-5A100VA - and MXZ-4A80VA - have been added.
E2E
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4. MSZ-CA MICROPROCESSOR CONTROL·················································39
Indoor unit models Outdoor unit models
MSZ-CA25VB MUZ-CA25VB
MSZ-CA35VB MUZ-CA35VB
4-1. “I FEEL CONTROL” OPERATION·····················································39
4-2. AUTO CHANGE OVER ··· AUTO MODE OPERATION······················44
4-3. COOL OPERATION·············································································45
4-4. DRY OPERATION ···············································································45
4-5. HEAT OPERATION ·············································································45
4-6. INDOOR FAN MOTOR CONTROL·····················································46
4-7. AUTO VANE OPERATION··································································46
4-8. TIMER OPERATION············································································47
4-9. EMERGENCY / TEST OPERATION ···················································48
4- 10. INVERTER SYSTEM CONTROL························································49
4-
11. OPERATION FREQUENCY CONTROL OF OUTDOOR UNIT··········51
4- 12. EXPANSION VALVE CONTROL (LEV CONTROL)···························52
5. MSZ-FA MICROPROCESSOR CONTROL ·················································54
Indoor unit models Outdoor unit models
MSZ-FA25VA MUZ-FA25VA MUZ-FA25VAH
MSZ-FA35VA MUZ-FA35VA MUZ-FA35VAH
5-1. COOL OPERATION·············································································55
5-2. DRY OPERATION ···············································································56
5-3. HEAT OPERATION ·············································································56
5-4. AUTO CHANGE OVER ··· AUTO MODE OPERATION······················58
5-5. INDOOR FAN MOTOR CONTROL·····················································59
5-6. OUTDOOR FAN MOTOR CONTROL·················································59
5-7. AUTO VANE OPERATION··································································59
5-8. i-see CONTROL OPERATION····························································61
5-9. AREA SETTING ··················································································62
5- 10 . PLASMA DUO OPERATION ······························································64
5- 11
. AUTO FRONT PANEL ········································································65
5-
12 . TIMER OPERATION ···········································································65
5- 13 . EMERGENCY / TEST OPERATION···················································66
5- 14.
INVERTER SYSTEM CONTROL························································67
5-
15. OPERATIONAL FREQUENCY CONTROL OF OUTDOOR UNIT·····69
5- 16. EXPANSION VALVE CONTROL (LEV CONTROL)···························70
6. MSZ-GA, MSZ-CB MICROPROCESSOR CONTROL ································72
Indoor unit models Outdoor unit models
MSZ-GA22VA MSZ-CB22VA
MSZ-GA25VA MSZ-CB25VA MUZ-GA25VA MUZ-GA25VAH
MSZ-GA35VA MSZ-CB35VA MUZ-GA35VA MUZ-GA35VAH
6-1. COOL OPERATION·············································································73
6-2. DRY OPERATION ···············································································74
6-3. HEAT OPERATION ·············································································74
6-4. AUTO CHANGE OVER ··· AUTO MODE OPERATION······················76
6-5. INDOOR FAN MOTOR CONTROL·····················································77
6-6. OUTDOOR FAN MOTOR CONTROL·················································77
6-7. AUTO VANE OPERATION··································································77
6-8. TIMER OPERATION············································································79
6-9. EMERGENCY / TEST OPERATION ···················································80
6- 10 . INVERTER SYSTEM CONTROL·······················································81
6-
11. OPERATIONAL FREQUENCY CONTROL OF OUTDOOR UNIT·····83
6- 12. EXPANSION VALVE CONTROL (LEV CONTROL)···························84
3
OBT06D--1qxp 07.3.2 9:22 AM Page 3

Indoor unit models Outdoor unit models
MSZ-GA50VA MUZ-GA50VA
MSZ-GA60VA MUZ-GA60VA
MSZ-GA71VA MUZ-GA71VA
6- 13 . COOL OPERATION············································································86
6- 14 . DRY OPERATION···············································································87
6-
15 . HEAT OPERATION·············································································88
6-
16 . AUTO CHANGE OVER ··· AUTO MODE OPERATION ·····················90
6- 17 . INDOOR FAN MOTOR CONTROL·····················································90
6-
18 . OUTDOOR FAN MOTOR CONTROL·················································91
6-
19 . AUTO VANE OPERATION··································································91
6- 20 . TIMER OPERATION ···········································································94
6-
21 . EMERGENCY/TEST OPERATION·····················································95
6-
22. INVERTER SYSTEM CONTROL ·······················································95
6-
23. OPERATIONAL FREQUENCY CONTROL OF OUTDOOR UNIT·····97
6- 24. EXPANSION VALVE CONTROL (LEV CONTROL)···························98
7. MCF MICROPROCESSOR CONTROL·····················································100
Indoor unit models Outdoor unit models
MCF-GA35VB MUCF-GA35VB
MCF-GA50VB MUCF-GA50VB
MCF-GA60VB MUCF-GA60VB
7-1. “I FEEL CONTROL” OPERATION ····················································100
7-2. COOL OPERATION············································································103
7-3. DRY OPERATION ··············································································103
7-4. FAN OPERATION···············································································103
7-5. AUTO VANE OPERATION·································································103
7-6. TIMER OPERATION···········································································105
7-7. EMERGENCY / TEST OPERATION ··················································105
8. MCFH MICROPROCESSOR CONTROL ··················································106
Indoor unit models Outdoor unit models
MCFH-GA35VB MUCFH-GA35VB
MCFH-GA50VB MUCFH-GA50VB
MCFH-GA60VB MUCFH-GA60VB
8-1. “I FEEL CONTROL” OPERATION ····················································106
8-2. COOL OPERATION············································································110
8-3. DRY OPERATION···············································································111
8-4. HEAT OPERATION·············································································111
8-5. AUTO VANE OPERATION··································································111
8-6. TIMER OPERATION···········································································113
8-7. EMERGENCY / TEST OPERATION···················································114
9. MFZ MICROPROCESSOR CONTROL······················································115
Indoor unit models
MFZ-KA25VA
MFZ-KA35VA
MFZ-KA50VA
9-1. COOL OPERATION···········································································117
9-2. DRY OPERATION··············································································117
9-3. HEAT OPERATION············································································117
9-4. AUTO CHANGE OVER ··· AUTO MODE OPERATION····················119
9-5. INDOOR FAN MOTOR CONTROL···················································120
9-6. OUTDOOR FAN MOTOR CONTROL···············································120
9-7. AUTO VANE OPERATION································································120
9-8. i-save OPERATION···········································································124
9-9. TIMER OPERATION··········································································125
9- 10. EMERGENCY / TEST OPERATION ·················································126
4
()
As for outdoor units SUZ-KA25/35/50VA.TH and SUZ-
KA25/35VAH.TH, refer to service manual OC322.
OBT06D--1qxp 07.3.2 9:22 AM Page 4

10. MSZ-HA MICROPROCESSOR CONTROL·············································127
Indoor unit models Outdoor unit models
MSZ-HA25VA MUZ-HA25VA
MSZ-HA35VA MUZ-HA35VA
10-1. COOL OPERATION·········································································128
10-2. DRY OPERATION ···········································································128
10-3. HEAT OPERATION ·········································································129
10-4. INDOOR FAN MOTOR CONTROL·················································130
10-5. AUTO VANE OPERATION······························································131
10-6. TIMER OPERATION········································································133
10-7. EMERGENCY / TEST OPERATION ···············································133
10-8 . INVERTER SYSTEM CONTROL····················································134
10-9
. OPERATIONAL FREQUENCY CONTROL OF OUTDOOR UNIT ······136
11. MSZ-GB MICROPROCESSOR CONTROL·············································137
Indoor unit models Outdoor unit models
MSZ-GB50VA MUZ-GB50VA
11-1. COOL OPERATION·········································································138
11-2. DRY OPERATION············································································139
11-3. HEAT OPERATION··········································································139
11-4. AUTO CHANGE OVER ··· AUTO MODE OPERATION··················141
11-5. INDOOR FAN MOTOR CONTROL·················································141
11-6. OUTDOOR FAN MOTOR CONTROL ·············································142
11-7. AUTO VANE OPERATION······························································142
11-8. TIMER OPERATION········································································144
11-9. EMERGENCY / TEST OPERATION················································145
11- 10 . INVERTER SYSTEM CONTROL ···················································145
11- 11. OPERATIONAL FREQUENCY CONTROL OF OUTDOOR UNIT ······147
11-
12. EXPANSION VALVE CONTROL (LEV CONTROL)·······················148
12. MXZ MICROPROCESSOR CONTROL···················································150
Outdoor unit models
MXZ-2A30VA
MXZ-2A40VA
MXZ-2A52VA
MXZ-3A54VA
MXZ-4A71VA
MXZ-4A80VA
MXZ-5A100VA
12-1. INVERTER SYSTEM CONTROL·····················································150
12-2. EXPANSION VALVE CONTROL (LEV CONTROL) ························153
12-3. OPERATIONAL FREQUENCY RANGE···········································159
12-4. HEAT DEFROSTING CONTROL·····················································160
12-5. DISCHARGE TEMPERATURE PROTECTION CONTROL·············161
12-6. REFRIGERANT RECOVERY CONTROL ON HEATING·················161
12-7. OUTDOOR FAN CONTROL·····························································161
12-8. PRE-HEAT CONTROL·····································································162
12-9. COOL OPERATION··········································································162
12- 10 . DRY OPERATION············································································163
12-
11 . HEAT OPERATION··········································································163
5
()
As for outdoor unit MXZ-8A140VA, refer to service manual
OC316.
OBT06D--1qxp 07.3.2 9:22 AM Page 5

6
MSC MICROPROCESSOR CONTROL
1
ON/OFF
FAN
TOO
WARM TOO COOL
VANE
MODE
ECONO COOL
STOP
START
HR.
MIN.
I FEEL COOL
DRY
PM
CLOCK
AM
RESET CLOCK
HEAT
/FAN
/
Open the front lid.
ON/OFF
TOO
COOL
PM
AM
TOO
WARM
Signal transmitting section
Operation display section
OPERATE /STOP
(ON /OFF) button
TEMPERATURE buttons
OPERATION SELECT button
FAN SPEED CONTROL button OFF-TIMER button
HR. button
MIN. button
(TIME SET button)
ON-TIMER button
RESET button
ECONO COOL button
VANE CONTROL button
CLOCK SET button
WIRELESS REMOTE CONTROLLER
Once the operation mode is set, the same operation mode can be repeated by simply turning OPERATE/STOP (ON/OFF) but-
ton ON. Indoor unit receives the signal with a beep tone.
When the system turns off, 3-minute time delay will operate to protect system from overload and compressor will not restart for
3 minutes.
MSC-CA20VB MSC-CB20VB MSC-GA20VB MU-GA20VB MUH-GA20VB MUX-2A28VB MUX-3A63VB
MSC-CA25VB MSC-CB25VB MSC-GA20VB MU-GA25VB MUH-GA25VB MUX-2A59VB MUX-2A70VB
MSC-CA35VB MSC-CB35VB MSC-GA35VB MU-GA35VB MUH-GA35VB MUX-3A60VB MUX-4A73VB
lighted
not lighted
Approx. 2 :
or more
Difference
between target
temperature
and room
temperature
Approx. 2 :
or less
This shows that the
air conditioner is
operating to reach
the target temperature.
Please wait until the
target temperature is
obtained.
This shows that the
room temperature is
approaching the
target temperature.
Operation state
Indication
Operation Indicator
Operation Indicator lamp
The operation indicator at the right side of the indoor
unit indicates the operation state.
INDOOR UNIT DISPLAY SECTION
•The following indication does not
depend on the shape of lamp.
1-1. COOL ( ) OPERATION
(1) Press OPERATE/STOP(ON/OFF) button. OPERATION INDICATOR lamp of the indoor unit turns on with a beep tone.
(2) Select COOL mode with OPERATION SELECT button.
(3) Press TEMPERATURE buttons (TOO WARM or TOO COOL button)to select the desired temperature.
The setting range is 16 ~ 31°C
1 :1.7 :
3:
2. Indoor fan speed control
Indoor fan operates continuously at the set speed by FAN SPEED CONTROL button regardless
of thermostat’s OFF-ON.
In Auto the fan speed is as follows. Initial temperature difference
Room temperature minus set temperature : 1.7 :or more·······························High
Room temperature minus set temperature : Between 1 and 1.7 :···················Med.
Room temperature minus set temperature : less than 1 :·································Low
Fan speed Difference between room
temperature and set tem-
perature during operation
-0.3 :0.3 :
1. Thermostat control
Thermostat is ON or OFF by difference between room temperature and set temperature
Initial temperature difference Thermostat
Room temperature minus set temperature : 0.3 :or more················································ON
Room temperature minus set temperature : less than -0.3 :············································OFF
Set temperature
Difference between room
temperature and set tem-
perature during operation
OBT06D--1qxp 07.3.2 9:22 AM Page 6

7
Compressor
Outdoor fan OFF
ON
( continuously at set speed)
Indoor fan ON
ON
OFF
② Time control
When the three conditions as follows have been satisfied for 1 hour and 45 minutes, the compressor stops for 3 minutes.
The indoor fan operates at the set speed.
a. Compressor has been continuously operating.
b. Indoor fan speed is Low or Med.
c. Room temperature is below 26°C.
When compressor stops, the accumulated time is cancelled. When compressor restarts, time counting starts
from the beginning.
Time counting also stops temporarily when the indoor fan speed becomes High or the room temperature exceeds
26°C. However, when two of the above conditions (b.and c.) are satisfied again, time accumulation is resumed.
Operation chart
Example
1-2. DRY ( ) OPERATION
(1) Press OPERATE/STOP(ON/OFF) button.
OPERATION INDICATOR lamp of the indoor unit turns on with a beep tone.
(2) Select DRY mode with the OPERATION SELECT button.
(3) The microprocessor reads the room temperature and determines the set tem-
perature. Set temperature is as shown on the right chart.
DRY operation will not function when the room temperature is 13°C or below.
(4) When DRY operation functions the fan speed is lower than COOL operation
except at (fan speed) Low.
The system for dry operation uses the same refrigerant circuit as the cooling
circuit.
The compressor and the indoor fan are controlled by the room temperature.
35
30
25
20
15
10
:
10 15 20 25 30 35
Set temperature
Initial room temperature
Set temperature and
initial room temperature in dry mode
:
2. Indoor fan speed control
Indoor fan operates at the set speed by FAN SPEED CONTROL button.
In Auto fan speed becomes Low.
3. The operation of the compressor and indoor / outdoor fan
<MU-GA20/GA25/GA35VB, MUH-GA20/GA25/GA35VB, MUX-2A28/2A59/3A60/3A63/2A70/4A73VB>
Compressor operates by room temperature control and time control.
Indoor fan and outdoor fan operate in the same cycle as the compressor.
•When the room temperature is 23°C or over:
When the thermostat is ON, the compressor repeats 8 minutes ON and 3 minutes OFF.
When the thermostat is OFF, the compressor repeats 4 minutes OFF and 1 minute ON.
•When the room temperature is under 23°C.
When the thermostat is ON, the compressor repeats 2 minutes ON and 3 minutes OFF.
When the thermostat is OFF, the compressor repeats 4 minutes OFF and 1 minute ON.
3. Coil frost prevention
① Temperature control
When the indoor coil thermistor RT12 reads 4°C or below(MSC-CA20/CA25/CB20/CB25/GA20/GA25VB) / 0°C or
below(MSC-CA35/CB35/GA35VB) for 5 minutes, the coil frost prevention mode starts.
The indoor fan operates at the set speed and the compressor stops for 5 minutes.
After that, if RT12 still reads below 4°C (MSC-CA20/CA25/CB20/CB25/GA20/GA25VB) / 0°C (MSC-CA35/CB35/GA35VB),
this mode is prolonged until RT12 reads over 4°C (MSC-CA20/CA25/CB20/CB25/GA20/GA25VB) / 0°C (MSC-
CA35/CB35/GA35VB).
-0.3 :0.3 :
1. Thermostat control
Thermostat is ON or OFF by difference between room temperature and set temperature.
Initial temperature difference Thermostat
Room temperature minus set temperature : 0.3 :or more················································ON
Room temperature minus set temperature : less than -0.3 :············································OFF
Set temperature
Difference between room
temperature and set tem-
perature during operation
OBT06D--1qxp 07.3.2 9:22 AM Page 7

8
4. Coil frost prevention
The operation is as same as coil frost prevention during COOL operation.(Refer to 1-1.3.)
However when coil frost prevention works while the indoor fan is OFF, its speed becomes set speed.
1-3. FAN ( ) OPERATION <MU-GA20/GA25/GA35VB, MUX-2A28/2A59/3A60/3A63/2A70/4A73VB>
(1) Press OPERATE/STOP(ON/OFF) button. OPERATION INDICATOR lamp of the indoor unit turns on with a beep tone.
(2) Select FAN mode with OPERATION SELECT button.
(3) Select the desired fan speed. When AUTO, it becomes Low.
Only indoor fan operates.
Outdoor unit does not operate.
1-4. HEAT ( ) OPERATION <MUH-GA20/GA25/GA35VB>
(1) Press OPERATE/STOP(ON/OFF) button.
OPERATION INDICATOR lamp of the indoor unit turns on with a beep tone.
(2) Select HEAT mode with the OPERATION SELECT button.
(3) Press TEMPERATURE buttons (TOO WARM or TOO COOL button) to select the desired temperature.
The setting range is 16 ~ 31°C.
2. Indoor fan speed control
(1) Indoor fan operates at the set speed by FAN SPEED CONTROL button.
In Auto the fan speed is as follows.
Set temperature minus room temperature: 1.7 : or more······················································· High
Set temperature minus room temperature: Between 1 and 1.7 : ··········································· Med.
Set temperature minus room temperature: less than 1
: ························································ Low
Initial temperature difference Fan speed
Difference between room
temperature and set tem-
perature during operation
Operation time chart
Example
Thermostat
Indoor fan
Outdoor fan
Compressor
ON ON
OFF
OFF
OFF
OFF
OFF
ON
ON
ON
ON
ON
ON
OFF
OFFOFF
(2) Cold air prevention control
1When the compressor is not operating,
(1) if the temperature of indoor coil thermistor RT12 is 0°C or less, the fan stops.
(2) if the temperature of indoor coil thermistor RT12 is more than 0°C, the fan operates at Very Low.
2When 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.
NOTE : If the temperature of RT12 reads from 18°C to 22°C at the air conditioner stating and also after defrosting,
this control works.
Released
Cold Air Prevention 18:22:
Fan speed
Set speed
Very Low or stop
-0.3 :0.3 :
Set temperature
Difference between room
temperature and set tem-
perature during operation
1. Thermostat control
Thermostat is ON or OFF by difference between room temperature and set temperature.
Initial temperature difference Thermostat
Room temperature minus set temperature : less than -0.3 :··············································ON
Room temperature minus set temperature : 0.3 :or more·················································OFF
1:1.7 :
3 :
8 minutes 1 minute
4 minutes
3 minutes
OBT06D--1qxp 07.3.2 9:22 AM Page 8

9
(3) Warm air control
When the following any conditions of 1(a. ~ c.) and the condition of 2are satisfied at the same time, warm air control
works.
1a.) When outdoor unit starts operating in HEAT mode.
b.) When cold air prevention has been released.
c.) When defrosting has been finished
2When 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 1-4.2.(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.
NOTE: As for high pressure protection, defrosting and R.V. coil control, refer to service manual for outdoor unit.
<Time condition> <Indoor fan speed>
less than 2 minutes Low
2 minutes to 4 minutes Med.
more than 4 minutes High
Mode
COOL mode of
"I FEEL CONTROL"
DRY mode of
"I FEEL CONTROL"
HEAT mode of
"I FEEL CONTROL"
Initial room temperature
MUH type
25: or more
23:or more,
less than 25:
less than 23:
MU & MUX type
25: or more
more than13:,
less than 25:
1-5. “I FEEL CONTROL”( ) OPERATION
(1) Press OPERATE/STOP(ON/OFF) button.
OPERATION INDICATOR lamp of the indoor unit turns on
with a beep tone.
(2) Select “I FEEL CONTROL”( ) mode with the OPERA-
TION SELECT button.
(3) The operation mode is determined by the initial room tem-
perature at start-up of the operation, as shown on the
right table.
Example
Previous operation
COOL mode of
“I FEEL CONTROL”
or COOL mode
•Once the mode is fixed, the mode does not change by room temperature afterwards.
•Under the ON-TIMER ( ) operation, mode is determined as follows.
When the system is stopped on the remote controller and restarted within 2 hours in “I FEEL CONTROL”( ) mode,
the system operates in previous mode automatically regardless of the room temperature.
Restart
COOL mode of
“I FEEL CONTROL”
Example
Previous operation
COOL mode of
“I FEEL CONTROL”
or COOL mode
When the system is restarted after 2 hours and more, the operation mode is determined by the room temperature at
start-up of the operation.
Restart
COOL or DRY or
HEAT mode of “I FEEL
CONTROL”that deter-
mined by room tem-
perature at start-up of
the operation.
Operation time chart
Operation time chart
OBT06D--1qxp 07.3.2 9:22 AM Page 9

10
Mode
COOL mode of
"I FEEL CONTROL"
DRY mode of
"I FEEL CONTROL"
HEAT mode of
"I FEEL CONTROL"
Initial room temperature Initial set temperature
26:
26: or more
25: or more,
less than 26:
23:or more,
less than25:
24:
Initial room temperature
minus 2:
Initial room temperature
minus 2:
❈1
more than 13:,
less than 25:
26: or more
25: or more,
less than 26:
less than 23:
MU & MUX type MUH type
❈1 When the system is restarted with the remote controller, the system operates with the previous set temperature regard-
less of the room temperature at restart.
(5) TEMPERATURES buttons
In “I FEEL CONTROL”( ) mode, set temperature is decided by the microprocessor based on the room temperature.
In addition, set temperature can be controlled by TOO WARM or TOO COOL buttons when you feel too cool or too
warm. Each time the TOO WARM or TOO COOL button is pressed, the indoor unit receives the signal and emits a beep
tone.
•Fuzzy control
When the TOO COOL or TOO WARM button is pressed, the microprocessor changes the set temperature, considering
the room temperature, the frequency of pressing TOO COOL or TOO WARM button and the user’s preference to heat or
cool. So this is called “Fuzzy control”, and works only in “I FEEL CONTROL”mode.
In DRY mode of “I FEEL CONTROL”, the set temperature doesn’t change.
…To raise the set temperature 1~2 degrees(°C)
…To lower the set temperature 1~2 degrees(°C)
(4) The initial set temperature is decided by the initial room temperature.
1-5-1. COOL mode of “I FEEL CONTROL”
1. Thermostat control
Thermostat control is as same as COOL OPERATION.(1-1.1.)
2. Indoor fan speed control
Indoor fan speed control is as same as COOL OPERATION.(1-1.2.)
3. Coil frost prevention
Coil frost prevention is as same as COOL OPERATION.(1-1.3.)
1-5-2. DRY mode of “I FEEL CONTROL”
1. Thermostat control
Thermostat control is as same as DRY OPERATION.(1-2.1.)
2. Indoor fan speed control
Indoor fan speed control is as same as DRY OPERATION.(1-2.2.)
3. The operation of the compressor and indoor/outdoor fan
The operation of the compressor and indoor/outdoor fan is as same as DRY OPERATION.(1-2.3.)
4. Coil frost prevention
Coil frost prevention is as same as DRY OPERATION.(1-2.4.)
1-5-3. HEAT mode of “I FEEL CONTROL”<MUH-GA20/GA25/GA35VB>
1. Thermostat control
Thermostat control is as same as HEAT OPERATION.(1-4.1.)
2. Indoor fan speed control
Indoor fan speed control is as same as HEAT OPERATION.(1-4.2.)
NOTE: As for high pressure protection, defrosting and R.V. coil control, refer to service manual for outdoor unit.
TOO
COOL
TOO
WARM
OBT06D--1qxp 07.3.2 9:22 AM Page 10

11
High High
Med. Low
COOL and DRY operation
HEAT operation
<MUH-GA20/GA25/GA35VB>
Vane angle is fixed to Angle 1.
Vane angle is fixed to Angle 4.
1-6. INDOOR FAN MOTOR CONTROL
(1) Rotational frequency feedback control
The indoor fan motor is equipped with a rotational frequency sensor, and outputs signal to the microprocessor to
feedback the rotational frequency. Comparing the current rotational frequency with the target rotational
frequency (High,Med.,Low), the microprocessor controls SR141 and adjusts fan motor electric current to make the
current rotational frequency close to the target rotational frequency. With this control, when the fan speed is switched,
the rotational frequency changes smoothly.
(2) Fan motor lock-up protection
When the rotational frequency feedback signal is not output for 12 seconds, (or when the microprocessor cannot detect
the signal for 12 seconds) the fan motor is regarded locked-up. Then the electric current to the fan motor is shut off. 3 min-
utes later, the electric current is applied to the fan motor again. During the fan motor lock-up, the OPERATION INDICA-
TOR lamp flashes on and off to show the fan motor abnormality.
1-7. AUTO VANE OPERATION
(1) Vane motor drive
These models are equipped with a stepping motor for the horizontal vane. The rotating direction, speed, and angle of
the motor are controlled by pulse signals (approx. 12V) transmitted from indoor microprocessor.
(2) The horizontal vane angle and mode change as follows by pressing the VANE CONTROL button.
(3) Positioning
The vane presses the vane stopper once to confirm the standard position and then set to the desired angle.
Confirming of standard position is performed in case of follows.
(a) When the OPERATE/STOP(ON/OFF) button is pressed.
(b) When the vane control is changed from AUTO to MANUAL.
(c) When the SWING is finished.
(d) When the test run starts.
(e) When the power supply turns ON.
(4) VANE AUTO ( ) mode
The microprocessor automatically determines the vane angle to make the optimum room temperature distribution.
FAN operation
<MU-GA20/GA25/GA35VB, MUX-A28/2A59/3A60/3A63/2A70/4A73VB>
(5) Dew prevention
During COOL or DRY operation at Vane Angle 4 or 5 when the cumulative operation time of compressor exceeds 1
hour, the vane angle automatically changes to Angle 1 for dew prevention.
(6) SWING MODE ( )
By selecting SWING mode with the VANE CONTROL button, the horizontal vane swings vertically. The remote controller
displays “”.
OBT06D--1qxp 07.3.2 9:22 AM Page 11

12
(7) Cold air prevention in HEAT operation <MUH-GA20/GA25/GA35VB>
When any of the following conditions occurs in HEAT operation, the horizontal vane angle changes to Angle 1 automat-
ically to prevent cold air blowing on users.
① Compressor is not operating.
➁ Defrosting is performed.
➂ Indoor coil thermistor RT12 reads 24:or below.
➃ Indoor coil thermistor RT12 temperature is raising from 24°C or below, but it does not exceed 28:.
Set position
Angle 1
Released
Cold air prevention 24:28:
Indoor coil thermistor
RT12 temperature
NOTE : If the temperature of RT12 reads from 24°C to 28°C at the air conditioner stating , this control works.
1-8. TIMER OPERATION
1. How to set the timer
(1) Press OPERATE/STOP(ON/OFF) button to start the air conditioner.
(2) Check that the current time is set correctly.
NOTE : Timer operation will not work without setting the current time. Initially “AM0:00”blinks at the current time display
of TIME MONITOR, so set the current time correctly with CLOCK SET button.
(3) Press ON or OFF TIMER buttons to select the operation.
“”button... AUTO START operation (ON timer)
“”button... AUTO STOP operation (OFF timer)
Horizontal vane
Temperature of indoor
coil thermistor RT12
more than 24°C
5
2
Downward blow time
(sec.)
22°C to 24°C
21°C to 22°C
20°C to 21°C
18°C to 20°C
17°C to 18°C
15°C to 17°C
15°C or less
5
8
11
14
17
20
23
Horizontal blow time
(sec.)
20
17
14
11
8
2
23
(8) ECONO COOL ( ) operation (ECONOmical operation)
When the ECONO COOL button is pressed in COOL mode, set temperature is automatically set 2°C higher.
Also the horizontal vane swings in various cycle according to the temperature of indoor heat exchanger(RT12).
SWING operation makes you feel cooler than set temperature. So, even though the set temperature is higher, the air
conditioner can keep comfort. As a result, energy can be saved.
ECONO COOL operation is cancelled when the ECONO COOL button is pressed once again or VANE CONTROL but-
ton is pressed or operation mode is changed.
NOTE : ECONO COOL operation does not work in COOL mode of “I FEEL CONTROL”.
<SWING operation>
In swing operation of ECONO COOL operation mode, the initial air flow direction is adjusted to “Horizontal”.
According to the temperature of indoor coil thermistor RT12 at starting of this operation, next downward blow time is
decided. Then when the downward blow has been finished, next upward blow time is decided.
For initial 10 min. the swing operation is performed in table G~H for quick cooling.
Also, after 10 min. when the difference of set temperature and room temperature is more than 2 degrees, the swing
operation is performed in table D~H for more cooling.
The air conditioner repeats the swing operation in various cycle as follows.
A
H
G
F
E
D
C
B
OBT06D--1qxp 07.3.2 9:22 AM Page 12

Lighted
Not lighted
Press once <Cool>
Press again <Heat>
Press once again <Stop>
wHeat is available only in MUH-GA20/GA25/GA35VB.
13
EMERGENCY OPERATION switch
PROGRAM TIMER
(Example 1) The current time is 8:00 PM.
The unit turns off at 11:00 PM, and on at 6:00 AM.
•OFF timer and ON timer can be used in combination.
•“”and “”display shows the order of OFF timer and ON timer operation.
PM
AM
(Example 2) The current time is 11:00 AM.
The unit turns on at 5:00 PM, and off at 9:00 PM.
NOTE : TIMER setting will be cancelled by power failure or breaker functioning.
PM
PM
2. Cancel
TIMER setting can be cancelled with ON or OFF TIMER buttons. (“”or “”)
To cancel ON timer, press “”button.
To cancel OFF timer, press “”button.
TIMER is cancelled and the display of set time disappears.
OPERATION INDICATOR lamp
(4) Press HR. and MIN. button to set the timer. Time setting is 10-minute units.
HR. and MIN. button will work when “”or “”mark is flashing.
These marks disappear in 1 minute.
After setting ON timer, check that OPERATION INDICATOR lamp of the indoor unit lights.
NOTE1 : Be sure to place the remote controller at the position where its signal can reach the air conditioner even during
TIMER operation, or the set time may deviate within the range of about 10 minutes.
NOTE2 : Reset the timer in the following cases, or the set time may deviate and other malfunctions may occur.
•A power failure occurs.
•The circuit breaker functions.
1-9. EMERGENCY / TEST OPERATION
In case of test run operation or emergency operation, use EMERGENCY OPERATION switch on the front of the
indoor unit. Emergency operation is available when the remote controller is missing, has failed or the batteries of remote
controller run down. The unit will start and OPERATION INDICATOR lamp will light.
The first 30 minutes of operation is the test run operation. This operation is for servicing. The indoor fan speed runs at
High speed and the system is in continuous operation. (The thermostat is ON.)
After 30 minutes of test run operation, the system shifts to EMERGENCY COOL [/ HEAT<MUH-GA20/GA25/GA35VB>]
MODE with a set temperature of 24°C. The fan speed shifts to Med. speed.
The coil frost prevention works even in emergency operation [, and defrosting<MUH-GA20/GA25/GA35VB> too].
In the test run or emergency operation, the horizontal vane operates in VANE AUTO ( ) mode.
Emergency operation continues until EMERGENCY OPERATION switch is pressed once again
(MU-GA20/GA25/GA35VB, MUX-2A28/2A59/3A60/3A63/2A70/4A73VB)/once or twice (MUH-GA20/GA25/GA35VB) or the
unit receives any signal from the remote controller.
In case of latter, normal operation will start.
NOTE : Do not press EMERGENCY OPERATION switch during normal operation.
•The following indication does not depend on the
shape of lamp.
OBT06D--1qxp 07.3.2 9:22 AM Page 13

14
1-10. OUTDOOR UNIT ACTUATOR CONTROL
ACTUATOR
ON
OFF
ON
OFF
ON
OFF
ON (OPEN)
OFF (CLOSE)
ON (OPEN)
OFF (CLOSE)
ON (OPEN)
OFF (CLOSE)
ON (OPEN)
OFF (CLOSE)
ON (CLOSE)
OFF (OPEN)
ON (CLOSE)
OFF (OPEN)
SOLENOID
VALVE
MUX-4A73VB
INDOOR UNIT
MC1
MC2
MF61
21R1
21R2
21R3
21R4
21RA
(BALANCE)
21RB
(BALANCE)
COMPRE-
SSOR
OUTDOOR
FAN MOTOR
A
ON
ON
OFF
OFF
–
–
–
–
OFF
ON
OFF
–
–
–
–
–
–
ON
ON
OFF
OFF
–
–
–
–
B
ON
OFF
ON
OFF
–
–
–
–
ANY UNIT ON
OFF
–
–
ON
OFF
–
–
–
–
ON
OFF
ON
OFF
–
–
–
–
C
–
–
–
–
ON
ON
OFF
OFF
OFF
–
–
–
–
ON
OFF
–
–
–
–
–
–
ON
ON
OFF
OFF
D
–
–
–
–
ON
OFF
ON
OFF
OFF
–
–
–
–
–
–
ON
OFF
–
–
–
–
ON
OFF
ON
OFF
ACTUATOR
ON
OFF
ON
OFF
ON
OFF
ON (OPEN)
OFF (CLOSE)
ON (OPEN)
OFF (CLOSE)
ON (CLOSE)
OFF (OPEN)
SOLENOID
VALVE
INDOOR UNIT
MC1
MC2
MF61
21R3
21R4
21RB
COMPRE-
SSOR
OUTDOOR
FAN MOTOR
A
ON
OFF
–
–
–
–
OFF
–
–
–
–
–
–
–
–
B
–
–
ON
ON
OFF
OFF
ANY UNIT ON
OFF
ON
OFF
–
–
ON
ON
OFF
OFF
C
–
–
ON
OFF
ON
OFF
OFF
–
–
ON
OFF
ON
OFF
ON
OFF
ACTUATOR
ON
OFF
ON
OFF
ON (CLOSE)
OFF (OPEN)
ON (OPEN)
OFF (CLOSE)
ON (OPEN)
OFF (CLOSE)
SOLENOID
VALVE
MUX-2A28VB
INDOOR UNIT
MC
MF
21R
(BALANCE)
21R1
21R2
COMPRE-
SSOR
OUTDOOR
FAN MOTOR
A
ON
ON
OFF
OFF
ANY UNIT ON
OFF
ON
ON
OFF
OFF
ON
OFF
–
–
B
ON
OFF
ON
OFF
OFF
ON
OFF
ON
OFF
–
–
ON
OFF
ACTUATOR
ON
OFF
ON
OFF
ON
OFF
MUX-2A59VB MUX-2A70VB
INDOOR UNIT
MC1
MC2
MF61
COMPRE-
SSOR
OUTDOOR
FAN MOTOR
A
ON
OFF
–
–
ANY UNIT ON
OFF
B
–
–
ON
OFF
OFF
MUX-3A60VB MUX-3A63VB
“–” means that the indoor unit is not related to the control of actuator.
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15
2MS MICROPROCESSOR CONTROL
WIRELESS REMOTE CONTROLLER
Mode
COOL mode of
"I FEEL CONTROL"
DRY mode of
"I FEEL CONTROL"
Initial room temperature
25:or more
more than 13:,
less than 25:
Once the operation mode is set, the same operation mode can
be repeated by simply turning OPERATE/STOP (ON/OFF) but-
ton ON.
Indoor unit receives the signal with a beep tone.
When the system turns off, 3-minute time delay will operate to
protect system from overload and compressor will not restart
for 3 minutes.
2-1. “I FEEL CONTROL”( ) OPERATION
(1) Press OPERATE/STOP (ON/OFF) button on the remote
controller. OPERATION INDICATOR lamp of the indoor
unit turns on with a beep tone.
(2) Select “I FEEL CONTROL”mode with OPERATION
SELECT button.
(3) The operation mode is determined by the room tempera-
ture at start-up of the operation.
MS-GA50VB MU-GA50VB
MS-GA60VB MU-GA60VB
MS-GA80VB MU-GA80VB
ON/OFF
FAN
TOO
WARM TOO COOL
VANE
MODE
ECONO COOL
STOP
START
HR.
MIN.
WIDE VANE
LONG
I FEEL COOL
DRY
PM
CLOCK
AM
RESET CLOCK
OPERATION SELECT button
FAN SPEED CONTROL button
OFF-TIMER button
HR. button
MIN. button
(TIME SET button)
ON-TIMER button
RESET button
ECONO COOL button
VANE button
(Horizontal vane button)
CLOCK SET button
LONG button
WIDE VANE button
(Vertical vane button)
ON/OFF
TOO
COOL
PM
AM
TOO
WARM
FAN
Signal transmitting section
Operation display section
OPERATE/ STOP
(ON/ OFF) button
TEMPERATURE buttons
Lighted
Not lighted
Approx.
2 : or more
Difference
between target
temperature
and room
temperature
Approx.
2 : or less
This shows that the
air conditioner is
operating to reach
the target temperature.
Please wait until the
target temperature is
obtained.
This shows that the
room temperature is
approaching the
target temperature.
Operation state
Indication
Operation Indicator
Operation Indicator lamp
The operation indicator at the right side of the indoor
unit indicates the operation state.
INDOOR UNIT DISPLAY SECTION
•The following indication applies regardless of
shape of the indicator.
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16
Previous operation
COOL mode of
“I FEEL CONTROL”
or COOL mode
•Once the mode is fixed, the mode does not change by room temperature afterwards.
•Under the ON-TIMER ( ) operation, mode is determined as follows.
When the system is stopped on the remote controller, and restarted within 2 hours in “I FEEL CONTROL”( ) mode,
the system operates in previous mode automatically regardless of the room temperature.
Previous operation
COOL mode of
“I FEEL CONTROL”
or COOL mode
When the system is restarted after 2 hours and more, the operation mode is determined by the room temperature at
start-up of the operation.
Restart
COOL mode of
“I FEEL CONTROL”
Restart
COOL or DRY mode
of “I FEEL CONTROL”
that determined by
room temperature at
start-up of the opera-
tion.
Model
COOL mode of
"I FEEL CONTROL"
DRY mode of
"I FEEL CONTROL"
Initial room temperature Initial set temperature
26:or more
25:to 26:
more than 13:, less than 25:
24:
Initial room temperature
minus 2:
Initial room temperature
minus 2:
❈1
(4) The initial set temperature is decided by the initial room temperature.
❈1 When the system is restarted with the remote controller, the system operates with the previous set temperature regard-
less of room temperature at restart.
The set temperature is calculated by the previous set temperature.
(5) TEMPERATURE buttons
In “I FEEL CONTROL”( ) mode, set temperature is decided by the microprocessor based on the room temperature.
In addition, set temperature can be controlled by TOO WARM or TOO COOL buttons when you feel too cool or too warm.
Each time the TOO WARM or TOO COOL button is pressed, the indoor unit receives the signal and emits a beep tone.
•Fuzzy control
When the TOO COOL or TOO WARM button is pressed, the microprocessor changes the set temperature, considering
the room temperature, the frequency of pressing TOO COOL or TOO WARM button and the user’s preference to heat or
cool. So this is called “Fuzzy control”, and works only in “I FEEL CONTROL”mode.
In DRY mode of “I FEEL CONTROL”, the set temperature doesn’t change.
…To raise the set temperature 1~2°C
…To lower the set temperature 1~2°C
TOO
COOL
TOO
WARM
Operation timer chart
Operation timer chart
Example
Example
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17
1. Indoor fan speed control
Indoor fan operates at the set speed by FAN SPEED CONTROL button.
In AUTO the fan speed is as follows. Initial temperature difference Fan Speed
Room temperature minus set temperature : 1.7 °C or more ···································High
Room temperature minus set temperature : Between 1 and 1.7 °C························Med.
Room temperature minus set temperature : less than 1 °C····································Low
2-1-1. COOL mode of “I FEEL CONTROL”
Difference between room
temperature and set temperature
during operation
1°C 1.7°C3°C
2. Coil frost prevention
① Temperature control
When the indoor coil thermistor RT12 reads 3°C or below(MS-GA50VB) /1°C or below(MS-GA60VB)/ RT12 or RT13
reads -1°C or below (MS-GA80VB), the coil frost prevention mode starts immediately.
However, the coil frost prevention doesn’t work for 5 minutes since the compressor has started.
The indoor fan operates at the set speed and the compressor stops for 5 minutes.
After that, if RT12 still reads below 3°C(MS-GA50VB)/ 1°C(MS-GA60VB)/ RT12 or RT13 still reads below-1°C
(MS-GA80VB) this mode prolonged until the RT12 reads over 3°C(MS-GA50VB)/ 1°C(MS-GA60VB) / RT12 or RT13 still
reads over-1°C(MS-GA80VB).
② Time control
When the three conditions as follows have been satisfied for 1 hour and 45 minutes, compressor stops for 3 minutes.
a. Compressor has been continuously operating.
b. Indoor fan speed is Low or Med.
c. Room temperature is below 26°C.
When compressor stops, the accumulated time is cancelled and when compressor restarts, time counting starts from the
beginning.
Time counting also stops temporarily when the indoor fan speed becomes High or the room temperature exceeds
26°C. However, when two of the above conditions (b.and c.) are satisfied again. Time accumulation is resumed.
Compressor
Outdoor fan OFF
ON
(continuously at set speed)
Indoor fan ON
ON
OFF
Operation chart
Example
4. Discharge temperature protection <MU-GA80VB>
The compressor is controlled by the temperature of discharge temperature thermistor RT62 for excess rise protection of
compressor discharge pressure.
•Compressor
When the temperature of discharge temperature thermistor RT62 goes to 120:or more, the compressor is turned OFF.
After 3 minutes since the compressor has been turned OFF, if the temperature of discharge temperature thermistor RT62
becomes 100:or less, the compressor is turned ON.
3. Outdoor fan speed control <MU-GA80VB>
Outdoor fan speed is controlled according to the temperature of ambient temperature thermistor RT63.
Outdoor fan Low operation : When the outside temperature decreases to 20°C or less.
Until the outside temperature goes to 22°C.
Outdoor fan High operation : Until the outside temperature decreases to 20°C or less.
When the outside temperature goes to 22°C.
Outdoor fan speed
20:22:
High
Ambient temperature
thermistor RT63 temperature Low
NOTE : When indoor fan speed is Low except FAN operation mode and the outside temperature is 30:or less, the
outdoor fan operates at Low.
Outdoor fan Low operation is cancelled according to the following conditions(1or 2):
1When the operation is not changed and the outside temperature goes to 33:or more.
2When the operation is changed. (Change to FAN operation mode / Change of the indoor fan speed)
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18
2-2. COOL ( ) OPERATION
(1) Press OPERATE/STOP (ON/OFF) button.
OPERATION INDICATOR lamp of the indoor unit turns on with a beep tone.
(2) Select COOL mode with OPERATION SELECT button.
(3) Press TEMPERATURE buttons.
(TOO WARM or TOO COOL button) to select the desired temperature.
The setting range is 16 ~ 31°C.
✻ Indoor fan continues to operate regardless of thermostat’s OFF-ON at set speed.
✻ Coil frost prevention is as same as COOL mode of “I FEEL CONTROL”.
Operation time chart
Example
3. Coil frost prevention
•The operation is as same as coil frost prevention during COOL mode of “I FEEL CONTROL”.
•Indoor fan operates at the set speed and the compressor stops for 5 minutes, because protection(Coil frost
prevention) has the priority.
However, when coil frost prevention works while the compressor is not operating, its speed becomes Low.
Thermostat
Indoor fan
Outdoor fan
Compressor
ON ON
OFF
OFF
OFF
OFF
OFF
ON
ON
ON
ON
ON
ON
OFF
OFF
OFF
2. The operation of the compressor and indoor/ outdoor fan
Compressor operates by room temperature control and time control.
Set temperature is controlled to fall 2°C from initial room temperature.
Indoor fan and outdoor fan operate in the same cycle as the compressor.
•When the room temperature is 23°C or over:
When the thermostat is ON, the compressor repeats 8 minutes ON and 3 minutes OFF.
When the thermostat is OFF, the compressor repeats 4 minutes OFF and 1 minute ON.
•When the room temperature is under 23°C.
When the thermostat is ON, the compressor repeats 2 minutes ON and 3 minutes OFF.
When the thermostat is OFF, the compressor repeats 4 minutes OFF and 1 minute ON.
1. Indoor fan speed control
Indoor fan operates at the set speed by FAN SPEED CONTROL button.
However, in AUTO fan operation, fan speed becomes Low.
2-1-2. DRY mode of “I FEEL CONTROL”
The system for dry operation uses the same refrigerant circuit as the cooling circuit.
The compressor and the indoor fan are controlled by the room temperature.
By such controls, indoor flow amounts will be reduced in order to lower humidity without much room temperature decrease.
4. Outdoor fan speed control <MU-GA80VB>
Outdoor fan speed control is as same as one of COOL mode of “I FEEL CONTROL”.
8 minutes 1 minute
4 minutes
3 minutes
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19
High
Rotational frequency
High
time
Med. Low
2-5. INDOOR FAN MOTOR CONTROL
(1) Rotational frequency feedback control
The indoor fan motor is equipped with a rotational frequency sensor, and outputs signal to the microprocessor to
feedback the rotational frequency. Comparing the current rotational frequency with the target rotational frequency
(High, Med., Low), the microprocessor controls SR141 and adjusts fan motor electric current to make the current rota-
tional frequency close to the target rotational frequency. With this control, when the fan speed is switched, the rotational
frequency changes smoothly.
(2) Fan motor lock-up protection
When the rotational frequency feedback signal has not output for 12 seconds, (or when the microprocessor cannot
detect the signal for 12 seconds) the fan motor is regarded locked-up. Then the electric current to the fan motor is shut
off. 3 minutes later, the electric current is applied to the fan motor again. During the fan motor lock-up, the OPERATION
INDICATOR Indicator lamp flashes on and off to show the fan motor abnormality.
AUTO
Horizontal
1234 5
Middle Downward Swing
2-6. AUTO VANE OPERATION
1. Horizontal vane
(1) Vane motor drive
These models are equipped with a stepping motor for the horizontal vane. The rotating direction, speed, and angle of
the motor are controlled by pulse signals (approx. 12V) transmitted from indoor microprocessor.
(2) The horizontal vane angle and mode change as follows by pressing the VANE button.
2-3. DRY ( ) OPERATION
(1) Press OPERATE/STOP (ON/OFF) button.
OPERATION INDICATOR lamp of the indoor
unit turns on with a beep tone.
(2) Select DRY mode with OPERATION SELECT
button.
(3) The microprocessor reads the room tempera-
ture and determines the set temperature. Set
temperature is as shown on the right chart.
Thermostat (SET TEMP.)does not work.
The other operations are same as DRY mode of
“I FEEL CONTROL”.
(4) DRY operation will not function when the room
temperature is 13°C or below.
2-4. FAN ( ) OPERATION
(1) Press OPERATE/STOP(ON/OFF) button.
OPERATION INDICATOR lamp of the indoor
unit turns ON with a beep tone.
(2) Select FAN mode with OPERATION
SELECT button.
(3) Select the desired fan speed. When AUTO, it
becomes Low.
Only indoor fan operates. Outdoor unit does not
operate.
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20
COOL and DRY operation FAN operation
Vane angle is fixed to Angle 1. Vane angle is fixed to Angle 4.
(4) VANE AUTO ( ) mode
The microprocessor automatically determines the horizontal vane angle and operation to make the optimum room tem-
perature distribution.
(5) STOP (operation OFF) and ON-TIMER standby
When the following cases occur, the horizontal vane returns to the closed position.
(a) When OPERATE/STOP (ON/OFF) button is pressed (POWER OFF).
(b) When the operation is stopped by the emergency operation.
(c) When ON-TIMER is on standby.
(6) Dew prevention
During COOL or DRY operation at Vane Angle 4 or 5 when the compressor cumulative operation time of compressor
exceeds 1 hour, the vane angle automatically changes to Angle 1 for dew prevention.
(7) SWING MODE ( )
By selecting SWING mode with VANE button, the horizontal vane swings vertically. The remote controller displays “”.
SWING mode is cancelled when VANE button is pressed once again.
(3) Positioning
The vane presses the vane stopper once to confirm the standard position and then moves to the set angle.
Confirming of standard position is performed in case of follows.
(a) When the power supply turns ON.
(b) When the operation starts or finishes (including timer operation).
(c) When the test run starts.
(d) When the vane control is changed AUTO to MANUAL (except SWING).
(e) When the SWING is finished (including ECONO COOL).
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