Mitsubishi MU-A WA, MUZ-A NA-U, MUZ-A NA, MSZ-A NA, MSY-A NA Service Technical Manual

SERVICE TECHNICAL GUIDE

CONTENTS

1. MS MICROPROCESSOR CONTROL ·················· 4

2. MSZ, MSY MICROPROCESSOR CONTROL ······7

3. MXZ MICROPROCESSOR CONTROL ··············21

4. MFZ MICROPROCESSOR CONTROL ·············· 35

SPLIT-TYPE AIR CONDITIONERS

No. OBT16

REVISED EDITION-H

Please void OBT16 REVISED EDITION-G.

Revision H:

• MXZ-3B24NA -1, MXZ-3B30NA -1 and MXZ-

4B36NA -

1

have been added.

Models

MS-A•WA · MU-A•WA
MSZ-A•NA · MUZ-A•NA, -

U

MSY-A•NA · MUY-A•NA
MSZ-FD•NA · MUZ-FD•NA, -

U

MSZ-FE•NA · MUZ-FE•NA
MSZ-D•NA · MUZ-D•NA, -

U

MSY-D•NA · MUY-D•NA
MSZ-GA•NA · MUZ-GA•NA, -

U

MSY-GA•NA · MUY-GA•NA
MSZ-GE•NA · MUZ-GE•NA
MSY-GE•NA · MUY-GE•NA

MFZ-KA•NA

· MXZ-A•NA, -

1

, -

2

· MXZ-B•NA, -

1

CONFIDENTIAL
(FOR INTERNAL USE ONLY)

2

Revision A:

• MXZ-3A30NA-

1

has been added.

Revision B:

• MXZ-2A20NA-

1

, MXZ-4A36NA, MSZ-FD, MSZ-D and MSY-D have been added.

Revision C:

• MXZ-2A20NA-2 has been added.

Revision D:

• MSZ-GA•NA and MSY-GA•NA have been added.

Revision E:

• MSZ-FE•NA, MSZ-GE•NA, MSY-GE•NA and MXZ-B•NA have been added.

Revision F:

• MXZ-2B20NA- 1, MXZ-3B24NA, MXZ-3B30NA, MXZ-4B36NA and MFZ-KA09/12/18NA have been added.

Revision G:

• MSZ-FE18NA, MSZ-GE24NA and MSY-GE24NA have been added.

Revision H:

• MXZ-3B24NA -1, MXZ-3B30NA -1 and MXZ-4B36NA -1 have been added.

3

1. MS MICROPROCESSOR CONTROL ··················································································································· 4

Indoor unit models Outdoor unit models

MS-A09/12WA MU-A09/12WA

1-1. COOL OPERATION ······································································································································· 4
1-2. DRY OPERATION ·········································································································································· 4
1-3. AUTO VANE OPERATION ····························································································································· 6

2. MSZ, MSY MICROPROCESSOR CONTROL ······································································································· 7

Indoor unit models Outdoor unit models

MSZ-A09/12/15/17/24NA MUZ-A09/12/15/17/24NA
MSY-A15/17/24NA MUY-A15/17/24NA
MSZ-FD09/12NA MUZ-FD09/12NA
MSZ-FE09/12/18NA MUZ-FE09/12/18NA
MSZ-D30/36NA MUZ-D30/36NA
MSY-D30/36NA MUY-D30/36NA
MSZ-GA24NA MUZ-GA24NA
MSY-GA24NA MUY-GA24NA
MSZ-GE06/09/12/15/18/24NA MUZ-GE09/12/15/18/24NA
MSY-GE09/12/15/18/24NA MUY-GE09/12/15/18/24NA

2-1. COOL OPERATION ······································································································································· 7
2-2. DRY OPERATION ·········································································································································· 8
2-3. HEAT OPERATION ········································································································································ 8
2-4. AUTO CHANGE OVER ··· AUTO MODE OPERATION ··············································································· 10
2-5. OUTDOOR FAN MOTOR CONTROL ·········································································································· 11
2-6. AUTO VANE OPERATION ··························································································································· 11
2-7. INVERTER SYSTEM CONTROL ················································································································· 12
2-8. OPERATIONAL FREQUENCY CONTROL OF OUTDOOR UNIT ······························································17
2-9. EXPANSION VALVE CONTROL (LEV CONTROL) ····················································································18
2-10. PRE-HEAT CONTROL ·································································································································

20

3. MXZ MICROPROCESSOR CONTROL ··············································································································· 21

Outdoor unit models

MXZ-2A20NA MXZ-3A30NA
MXZ-4A36NA
MXZ-2B20NA MXZ-3B24NA
MXZ-3B30NA MXZ-4B36NA

3-1. INVERTER SYSTEM CONTROL ················································································································· 21
3-2. EXPANSION VALVE CONTROL (LEV CONTROL) ····················································································23
3-3. OPERATIONAL FREQUENCY RANGE ······································································································ 29
3-4. HEAT DEFROSTING CONTROL ·················································································································

31

3-5.

DISCHARGE TEMPERATURE PROTECTION CONTROL ·················································································· 31

3-6. OUTDOOR FAN CONTROL ························································································································

32

3-7. PRE-HEAT CONTROL ·································································································································

33

3-8.

COOL OPERATION ···············································································································································33

3-9.

DRY OPERATION ··················································································································································34

3-10. HEAT OPERATION ······································································································································

34

4. MFZ MICROPROCESSOR CONTROL ··············································································································· 35

Indoor unit models

MFZ-KA09NA
MFZ-KA12NA
MFZ-KA18NA

4-1. COOL OPERATION ···································································································································· 35
4-2. DRY OPERATION ······································································································································· 35
4-3. HEAT OPERATION ····································································································································· 36
4-4. AUTO CHANGE OVER ··· AUTO MODE OPERATION ············································································· 37
4-5. INDOOR FAN MOTOR CONTROL ············································································································· 37
4-6. AUTO VANE OPERATION ·························································································································· 38

4

1-1. COOL ( ) OPERATION

2. Indoor fan speed control

Indoor fan operates continuously at the set speed by FAN SPEED CONTROL button regardless of the thermostat's OFF­ON.
In AUTO the fan speed is as follows.

1. Thermostat control

Thermostat turns ON or OFF by the difference between room temperature and set temperature.

1-2. DRY ( ) OPERATION

Set temperature is as shown on the right chart.
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.

95(35)

86(30)

77(25)

68(20)

59(15)

50(10)

50 59 68 77 86 95

Set temperature [°F(°C)]

Initial room temperature [°F(°C)]

Set temperature and
initial room temperature in dry mode

(10) (15) (20) (25) (30) (35)

3. Coil frost prevention

Temperature control

When the indoor coil thermistor RT12 reads 37°F (3°C) or below the coil frost prevention mode starts immediately.
However, the coil frost prevention does not 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 the indoor coil thermistor still reads below 37°F (3°C), this mode is prolonged until the indoor coil thermistor
reads over 37°F (3°C).

Time control

When the 3 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 79°F (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 79°F (26°C).
However, when two of the above conditions (b. and c.) are satisfied again, time accumulation is resumed.

Compressor
Outdoor fan

Indoor fan

Operation chart
Example

OFF

( Continuously at set speed)

ON

ON

1

MS MICROPROCESSOR CONTROL

Room temperature minus

Thermostat

set temperature (Initial)

ON -1.8°F(-1°C) or more
OFF less than -1.8°F(-1°C)

Room temperature minus

Fan speed

set temperature (Initial)
High 3.15°F(1.75°C) or more
Med. between 1.8 and 3.15°F
Low

less than 1.8°F(1°C)

Room temperature minus
set temperature (During operation)

-1.8°F
(-1°C)

-1.35°F

(-0.75°C)

Room temperature minus
set temperature (During operation)

5.4°F

1.8°F
(1°C)

3.15°F
(1.75°C)

(3°C)

5

1. Thermostat control

Thermostat turns ON or OFF by the difference between room temperature and set temperature.

2. Indoor fan speed control

Indoor fan operates at the set speed by FAN SPEED CONTROL button.
When thermostat OFF (compressor OFF), fan speed becomes Very Low.

In AUTO the fan speed is as follows.

4. Coil frost prevention

Coil frost prevention is as same as COOL mode. (2-1.3.)
The indoor fan maintains the actual speed of the moment. However, when coil frost prevention works while the compressor
is not operating, its speed becomes the set speed.

3. The operation of the compressor and indoor/outdoor fan

Compressor operates by room temperature control and time control.
Set temperature is controlled to fall 4°F (2°C) from initial room temperature.
Indoor fan and outdoor fan operate in the same cycle as the compressor.

• When the room temperature is 73°F (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 73°F (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.

Operation time chart
Example

Thermostat

Indoor fan

Outdoor fan
Compressor

ON

ON

ON

OFF

OFF

OFF

8 minutes

1 minute

4 minutes

3 minutes

Room temperature minus

Thermostat

set temperature (Initial)

ON -3.6°F(-2°C) or more
OFF less than -3.6°F(-2°C)

Room temperature minus

Fan speed

set temperature (Initial)
High 3.15°F(1.75°C) or more
Med. between 1.8 and 3.15°F
Low

less than 1.8°F(1°C)

Room temperature minus
set temperature (During operation)

-3.6°F
(-2°C)

-1.35°F

(-0.75°C)

Room temperature minus
set temperature (During operation)

4.5°F

(2.5°C)

3.15°F

1.8°F
(1.75°C)

(1°C)

6

1-3. AUTO VANE OPERATION

1. Horizontal vane

ECONO COOL (

) operation (ECONOmical operation)
When ECONO COOL button is pressed in COOL mode, set temperature is automatically set 3.6°F (2°C) higher than that
in COOL mode.
Also the horizontal vane swings in various cycle according to the temperature of indoor heat exchanger (indoor coil
thermistor).
SWING operation makes you feel cooler than set temperature. So, even though the set temperature is higher than that
in COOL mode, the air conditioner can keep comfort. As a result, energy can be saved.
To cancel this operation, select a different mode or press one of the following buttons in ECONO COOL operation:
ECONO COOL or VANE CONTROL button.

<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 at starting of this operation, next downward blow time is decided.
Then when the downward blow has been finished, next horizontal blow time is decided.
For initial 10 minutes the swing operation is performed in table G~H for quick cooling.
Also, after 10 minutes when the difference of set temperature and room temperature is more than 3.6°F (2°C), the
swing operation is performed in table D~H for more cooling.
The air conditioner repeats the swing operation in various cycle as follows.

Temperature of indoor

coil thermistor (°F/°C)

Downward blow time

(second)

Horizontal blow time

(second)
A 59/15 or less 2 23
B 59/15 to 63 /17 5 20
C 63/17/ to 64/18 8 17
D 64/18 to 68/20 11 14
E 68/20 to 70/21 14 11
F 70/21 to 72/22 17 8
G 72/22 to 75/24 20 5
H more than 75/24 23 2

7

2-1. COOL ( ) OPERATION

2. Indoor fan speed control

Indoor fan operates continuously at the set speed by FAN SPEED CONTROL button regardless of the thermostat's OFF-

ON.

In AUTO the fan speed is as follows.

1. Thermostat control

Thermostat turns ON or OFF by the difference between room temperature and set temperature.

3. Coil frost prevention

The compressor operational frequency is controlled to prevent the temperature of indoor heat exchanger from falling exces­sively.
The compressor is turned OFF for 5 minutes when the temperature of indoor coil thermistor continues 37°F (3°C) or less for

5 minutes or more.
The indoor fan maintains the actual speed of the moment.

4. Low outside temperature operation

If the outside temperature falls to 64°F (18°C) or less during operation in COOL mode, the unit will switch to the low outside
temperature operation mode.
<Operation>
(1) Outdoor fan control

The outdoor fan rotational speed slows down to maintain sufficient cooling capacity.
NOTE: Even when the unit is in the "thermostat-off" status under the low outside temperature operation mode, the out-

door fan rotation does not stop.
(2) Dew drop prevention
When the ambient temperature thermistor reads 14°F (-10°C) or less (the set temperature is different depending on the

models), as coil frost or dew drop from indoor unit may occur, the compressor turns OFF with the outdoor fan OFF for

prevention of them.
(3) Outdoor temperature detecting control
To detect the exact outdoor temperature in this mode, the compressor turns OFF but the outdoor fan stays ON for 3

minutes once 1 hour. If the outdoor temperature rises over about 64°F (18°C), the unit goes back to the normal COOL

mode. If the outside temperature stays below about 64°F (18°C), the unit continues to run in the low outside tempera-

ture operation mode.

Other protections work as well as in the normal COOL mode.

2

MSZ, MSY MICROPROCESSOR CONTROL

Room temperature minus

Thermostat

ON -1.8°F(-1°C) or more
OFF less than -1.8°F(-1°C)

Fan speed

High 3.15°F(1.75°C) or more
Med. between 1.8 and 3.15°F
Low

set temperature (Initial)

Room temperature minus
set temperature (Initial)

less than 1.8°F(1°C)

Room temperature minus
set temperature (During operation)

-1.8°F
(-1°C)

Room temperature minus
set temperature (During operation)

5.4°F

1.8°F
(1°C)

3.15°F
(1.75°C)

(3°C)

-1.35°F

(-0.75°C)

8

2-2. DRY ( ) OPERATION

Set temperature is as shown on the right chart.
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.

95(35)

86(30)

77(25)

68(20)

59(15)

50(10)

50 59 68 77 86 95

Set temperature [°F(°C)]

Initial room temperature [°F(°C)]

Set temperature and
initial room temperature in dry mode

(10) (15) (20) (25) (30) (35)

1. Thermostat control

Thermostat turns ON or OFF by the difference between room temperature
and set temperature.

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.

2-3. HEAT ( ) OPERATION (MSZ)

1. Thermostat control

Thermostat turns ON or OFF by difference between room temperature and set temperature.

2. Indoor fan speed control

Indoor fan operates at the set speed by FAN SPEED CONTROL button.
When the thermostat turns OFF (compressor OFF), fan speed becomes Very Low.
In AUTO the fan speed is as follows.

3. Coil frost prevention

Coil frost prevention is as same as COOL mode. (2-1.3.)
The indoor fan maintains the actual speed of the moment. However, when coil frost prevention works while the compressor
is not operating, its speed becomes the set speed.

4. Low outside temperature operation

Low outside temperature operation is as same as COOL mode. (2-1.4.)

High 3.15°F(1.75°C) or more
Med. between 1.8 and 3.15°F
Low

less than 1.8°F(1°C)

3.15°F
(1.75°C)

4.5°F

(2.5°C)

1.8°F
(1°C)

Fan speed

Room temperature minus
set temperature (Initial)

Room temperature minus
set temperature (During operation)

ON less than 3.6°F(2°C)
OFF 3.6°F(2°C) or more

3.15°F

(1.75°C)

3.6°F
(2°C)

Thermostat

Room temperature minus
set temperature (Initial)

Room temperature minus
set temperature (During operation)

High
Med.
Low

Fan speed

Set temperature minus room
temperature (During operation)

Set temperature minus
room temperature (Initial)

Between 0.45 and 3.6°F

3.6°F(2°C) or more

Less than 0.45°F(0.25°C)

0.45°F

(0.25°C)

3.15°F

(1.75°C)

3.6°F
(2°C)

7.2°F
(4°C)

ON less than 1.8°F(1°C)
OFF 1.8°F(1°C) or more

1.35°F

(0.75°C)

1.8°F
(1°C)

Thermostat

Room temperature minus
set temperature (Initial)

Room temperature minus
set temperature (During operation)

(MSZ-FE18 MSZ-GE24)

(Other models)

Room temperature minus

Thermostat

ON -3.6°F(-2°C) or more
OFF less than -3.6°F(-2°C)

set temperature (Initial)

Room temperature minus
set temperature (During operation)

-3.6°F
(-2°C)

-1.35°F

(-0.75°C)

9

(2) Cold air prevention control

MSZ-A09/12/15/17 MSZ-FD MSZ-FE MSZ-D MSZ-GE

When the compressor is not operating,

(

) if the temperature of room temperature thermistor is less than 66°F (19°C), the fan stops.

( ) if the temperature of room temperature thermistor is 66°F (19°C) or more and

(

) if the temperature of indoor coil thermistor is less than 32°F (0°C), the fan stops.

(

) if the temperature of indoor coil thermistor is 32°F (0°C) or more, the fan operates at Very Low.

When the compressor is operating,

(

) if the temperature of indoor coil thermistor is 104°F (40°C) or more, the fan operates at set speed.

(

) if the temperature of indoor coil thermistor is less than 104°F (40°C) and

( ) if heating operation starts after defrosting, the fan stops.
(

) if the temperature of room temperature thermistor is 66°F (19°C) or less, the fan stops.

(

)

if the temperature of room temperature thermistor is more than 66°F (19°C), the fan operates at Very Low.

NOTE: When 4 minutes (

MSZ-FE18 MSZ-GE24)/

3 minutes (Other models) have passed since the compressor started

operation, this control is released regardless of the temperature of room temperature thermistor and indoor coil
thermistor.

MSZ-A24 MSZ-GA

When the compressor is not operating,

(

) if the temperature of room temperature thermistor is 59°F (15°C) or less, or temperature of indoor coil thermis-

tor is less than 64°F (18°C), the fan stops.

(

) if the temperature of room temperature thermistor is more than 59°F (15°C), or temperature of indoor coil

thermistor is more than 64°F (18°C), the fan operates at Very Low.

When the compressor is operating,

( ) if the temperature of indoor coil thermistor is 64°F (18°C) or more, the fan operates at set speed.
(

) if the temperature of indoor coil thermistor is less than 64°F (18°C) and

( ) if heating operation starts after defrosting, the fan stops.
(

) if the temperature of room temperature thermistor is 59°F (15°C) or less, the fan stops.

(

)

if the temperature of room temperature thermistor is more than 59°F (15°C), the fan operates at Very Low.

NOTE: When 3 minutes have passed since the compressor started operation, this control is released regardless of the

temperature of room temperature thermistor and indoor coil thermistor.

(3) Warm air control (MSZ-FD MSZ-FE MSZ-GE)

When the following any condition of

(a. ~ c.) and the condition of are satisfied at the same time, warm air control

works.

a.) Fan speed is used in MANUAL.
b.) When cold air prevention has been released.
c.) When defrosting has been finished.

When the temperature of indoor coil thermistor is less than 104°F (40°C).
When warm air control works, the fan speed changes as follows to blow out warm air gradually.

Gradation of fan speed in initial

<Time condition> <Indoor fan speed>
Less than 4 minutes ------------ Low
4 to 8 minutes -------------------- Med.
More than 8 minutes ----------- High

<Time condition> <Indoor fan speed>
Less than 2 minutes ------------ Low
2 to 4 minutes -------------------- Med.
More than 4 minutes ----------- High or Super high

The upper limit of the fan speed in MANUAL is the set speed.
When the temperature of indoor coil thermistor has been 104°F (40°C) or more, or when the set speed has been
changed, this control is released and the fan speed is the set speed.

3. Overload starting

When the room temperature thermistor reads 64°F (18°C) or more, the compressor runs with its maximum frequency regu­lated for 10 minutes after the start-up.

4. Defrosting

(1) Starting conditions of defrosting

When the following conditions a) ~ c) are satisfied, the defrosting starts.
a) The defrost thermistor reads about 30.2°F (-1°C) or less.
b) The cumulative operation time of the compressor has reached any of the set values (defrost interval: 40-150 min-

utes).

c) More than 5 minutes have passed since the start-up of the compressor.

The defrost interval is decided by the previous defrosting time. The next defrost interval extends or shortens 0-20

minutes compared with the previous defrost interval.

(MSZ-FE18 MSZ-GE24)

(Other models)

10

set position

set speed

set position

set speed

Indoor fan

Compressor normal

Outdoor fan

R.V. coil

(21S4)

OFF (COOL)

OFF

Maximum frequency

horizontal

Horizontal vane

Very Low (temperature of indoor coil thermistor > 64 °F)

30

seconds

30

seconds

30

seconds

40

seconds

5 seconds 5 seconds

40

seconds

OFF

(39°C)

(18°C)

OFF

OFF

ON (HEAT)

ON ON

ON (HEAT)

horizontal (temperature of indoor coil thermistor < 102 °F)

<Outdoor unit>

<Indoor unit>

Time chart of defrosting in HEAT mode (reverse type)

2-4. AUTO CHANGE OVER ··· AUTO MODE OPERATION (MSZ)

Once desired temperature is set, unit operation is switched automatically between COOL and HEAT operation.

1. Mode selection

(1) Initial mode

At first indoor unit operates only indoor fan with outdoor unit OFF for 3 minutes to detect present room temperature.
Following the conditions below, operation mode is selected.

If the room temperature thermistor reads more than set temperature, COOL mode is selected.
If the room temperature thermistor reads set temperature or less, HEAT mode is selected.

(2) Releasing conditions of defrosting

Defrosting is released when any one of the following conditions is satisfied:
a) The defrost thermistor continues to read "Defrost finish temperature" for 30 seconds.

Refer to "CHANGE IN DEFROST SETTING of SERVICE FUNCTIONS in OUTDOOR UNIT SERVICE MANUAL".
b) Defrosting time has exceeded 10 minutes.
c) Any other mode than HEAT mode is set during defrosting.

11

(2) Mode change

In case of the following conditions, the operation mode is changed.

COOL mode changes to HEAT mode when 15 minutes have passed with the room temperature 2 - 4°F (1 - 2°C)

below the set temperature.

HEAT mode changes to COOL mode when 15 minutes have passed with the room temperature 2 - 4°F (1 - 2°C)

above the set temperature.

In the other cases than the above conditions, the present operation mode is continued.

NOTE1: Mode selection is performed when multi standby (refer to NOTE2) is released and the unit starts operation with

ON-timer.

NOTE2: When two or more indoor units are operating simultaneously, the indoor unit, which is operating in AUTO ( ),

might not be able to change over the operating mode (COOL ↔ HEAT) and becomes the standby state.

(3) Indoor fan control/ Vane control

As the indoor fan speed and the horizontal vane position depend on the selected operation mode, when the operation
mode changes over, they change to the exclusive ones.

2-5. OUTDOOR FAN MOTOR CONTROL

Fan speed is switched according to the compressor frequency.

2-6. AUTO VANE OPERATION

1. Horizontal vane

(1) Cold air prevention in HEAT operation (MUZ)

When any of the following conditions occur in HEAT operation, the vane angle changes to Horizontal position automati­cally to prevent cold air blowing on users.

Compressor is not operating.
Defrosting is performed.
Indoor coil thermistor temperature does not exceed 102°F (39°C) within about 3 minutes after compressor starts.

NOTE: When 2 or more indoor units are operated with multi outdoor unit, even if any indoor unit turns thermostat OFF,

this control does not work in the indoor unit.

(2) ECONO COOL ( ) operation (ECONOmical operation) (Excluding MSZ-FD and MSZ-FE09/12)

When ECONO COOL button is pressed in COOL mode, set temperature is automatically set 3.6°F (2°C) higher than that
in COOL mode.
Also the horizontal vane swings in various cycle according to the temperature of indoor heat exchanger (indoor coil
thermistor).
SWING operation makes you feel cooler than set temperature. So, even though the set temperature is higher than that
in COOL mode, the air conditioner can keep comfort. As a result, energy can be saved.
To cancel this operation, select a different mode or press one of the following buttons in ECONO COOL operation:
ECONO COOL or VANE CONTROL button.

<Relation between compressor frequency and fan speed>

Compressor frequency (Hz)

Down Up

MUZ-A MUY-A

MUZ-FD

MUZ-FE09/12

MUZ-GA MUY-GA

MUZ-GE12/15/18 MUY-GE12/15/18

33 44

MUZ-D MUY-D

MUZ-GE09 MUY-GE09

39 54

MUZ-FE18

MUZ-GE24 MUY-GE24

33 43

Fan speed

High

Low

Down Up

Compressor frequencyMin. Max.

12

<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 horizontal blow time is decided.
For initial 10 minutes the swing operation is performed in table G~H for quick cooling.
Also, after 10 minutes when the difference of set temperature and room temperature is more than 3.6°F (2°C), the
swing operation is performed in table D~H for more cooling.
The air conditioner repeats the swing operation in various cycle as follows.

2-7. INVERTER SYSTEM CONTROL

2-7-1. Inverter main power supply circuit

MUZ-A09/12/15/17 MUY-A15/17 MUZ-FD MUZ-FE09/12 MSZ-GE06/09/12/15/18 MUY-GE09/12/15/18

POWER
SUPPLY

NOISE
FILTER
CIRCUIT

RESISTOR

SWITCHING
POWER
TRANSISTOR

RELAY

SMOOTHING
CAPACITOR

CURRENT
TRANSFORMER

COMPRESSOR

DIODE
MODULE1

DIODE
MODULE2

REACTOR

P

W

V

U

N

INTELLIGENT

POWER

MODULE

U

W

MS

3~

V

+

BOOSTER CHOPPER CIRCUIT

+

-

~~

+

-

~~

Temperature of indoor

coil thermistor (°F/°C)

Downward blow time

(second)

Horizontal blow time

(second)
A 59/15 or less 2 23
B 59/15 to 63/17 5 20
C 63/17 to 64/18 8 17
D 64/18 to 68/20 11 14
E 68/20 to 70/21 14 11
F 70/21 to 72/22 17 8
G 72/22 to 75/24 20 5
H more than 75/24 23 2

Function of main parts

NAME FUNCTION

INTELLIGENT POWER MODULE It supplies 3-phase AC power to compressor.

SMOOTHING CAPACITOR

It stabilizes the DC voltage and supplies it to INTELLIGENT POWER MOD­ULE.

CURRENT TRANSFORMER It measures the current of the compressor motor.

DIODE MODULE 1 It converts the AC voltage to DC voltage.

RESISTOR

It absorbs the rush current not to run into the main power supply circuit when
the electricity turns ON.

RELAY

It keeps the RESISTOR, which restricts rush current, short-circuited while the
compressor is operating.

BOOSTER
CHOPPER
CIRCUIT

DIODE MODULE 2

It improves power factor.
It controls the bus-bar voltage.

SWITCHING POWER TRANSISTOR

REACTOR