Mitsubishi Electric MSH24WN, MUH24WN, MSH24WNW Service Manual

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SPLIT-TYPE, HEAT PUMP AIR CONDITIONERS

CUS

Revision:

●PARTS LIST have been partially modified.

●Please void OB310.

SERVICE MANUAL

Wireless type Models

MSH24WN (W) · MUH24WN

No. OB310

REVISED EDITION-A

INDOOR UNIT Indication of model name MSH24WN

Remote controller

OUTDOOR UNIT Indication of model name MUH24WN

CONTENTS

1. FEATURES·························································3

2. PART NAMES AND FUNCTIONS······················4

3. SPECIFICATION·················································6

4. DATA···································································8

5. OUTLINES AND DIMENSIONS·······················13

6. WIRING DIAGRAM ··········································15

7. REFRIGERANT SYSTEM DIAGRAM··············16

8. MICROPROCESSOR CONTROL ····················17

9. SERVICE FUNCTIONS ····································29

10. TROUBLESHOOTING ······································31

11. DISASSEMBLY INSTRUCTIONS·····················44

12. PARTS LIST······················································48

13. OPTIONAL PARTS ······················BACK COVER

The Slim Line. From Mitsubishi Electric.

Revision:

CAPILLARY TUBE (TAPER PIPE) [0.17X[0.12X11-13/16 CAPILLARY TUBE (TAPER PIPE) [0.17X[0.12X1-31/32

E02 785 936

E02 529 936

Part number

Part name

Model

MUH24WN

Page

• Parts No. has been changed due to the color change of outdoor unit parts. WHITE➔NEW WHITE (Brighter)

• Capillary tubes have been added to parts list.

LCD wireless remote controller

SWING

FEATURES

MSH24WN

MUH24WN

Model

MSH24WN

Cooling capacity

22,000 Btu/h

Heating capacity

23,600 Btu/h

SEER

10.0

HSPF(

6.8/5.9

)

44/55

“I FEEL CONTROL” IN OUR LCD WIRELESS REMOTE CONTROLLER WITH ON/OFF PROGRAM TIMER

Mitsubishi Electric’s new wireless remote controller incorporates a number of advanced features that provide even greater con-

trol and ease-to-use. It has a liquid crystal display which indicates such information as mode, fan speed and temperature selected as well as the programmed ON/OFF timer. It is also equipped with “I Feel Control”, a unique Mitsubishi Electric feature that allows the user to adjust the temperature to exactly the level he or she wants simply by tapping the button that describes present conditions : “Too Cool” or “Too Warm”. The optimum temperature set this way is then memorized for immediate recall whenever the air conditioner is used again.

Select desired air flow direction. REMOTE-CONTROL OPERATION MODE

Using the remote controller, you can select from five airflow settings to match room layout and the location of people. Also, you can set the vane to swing automatically.

AUTO-RESTART FUNCTION

The auto-restart function restarts the equipment when power is

restored following an outage automatically. Operation resumes in the mode in which the equipment was running immediately before the outage.

HIGH PERFORMANCE ROTARY COMPRESSOR

The advanced design of Mitsubishi Electric’s powerful and energy

efficient rotary compressor results in lower operating costs and longer service life.

Installation plate Installation plate fixing screw 4 x 25 mm(0.16 x 0.98 in.) Remote controller holder Fixing screw for 3 3.5 x 16 mm(0.14 x 0.63 in.) (Black) Battery (AAA) for remote controller Wireless remote controller Felt tape (Used for left or left-rear piping)

1 7 1 2 2 1 1

1 2 3 4 5 6 7

MSH24WN

PART NAMES AND FUNCTIONS

INDOOR UNIT

MSH24WN

Deodorizing filter (option) (Gray sponge type)

Air cleaning filter (option) (White bellows type)

Front panel

Air filter

Vertical vane

Operation section

(When the grille is opened)

Grille

Air inlet

Remote control receiving section

Horizontal vane

Remote controller

Display section

Operation indicator lamp

Operation Indicator

Emergency operation switch

Receiving section

ACCESSORIES

OUTDOOR UNIT

MUH24WN

REMOTE CONTROLLER

ON/OFF

TOO

COOL

TOO

WARM

ON/OFF

FAN

TOO

WARM

TOO

COOL

VANE

MODE

STOP

START

HR.

MIN.

WIDE VANE

LONG

I FEEL

COOL

HEAT

DRY

CLOCK

RESET CLOCK

Open the front lid.

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

VANE button

(Horizontal vane button)

CLOCK SET button

LONG button

WIDE VANE button

(Vertical vane button)

MSH24WN

Item

Model

Capacity

Power consumption

EER

[SEER]

HSPF IV

(V) COP INDOOR UNIT MODEL External finish

Power supply Max. fuse size

(time delay)

/ Disconnect switch

Min. circuit ampacity Fan motor Auxiliary heater

Airflow Low—Med.—High Moisture removal

Sound level Low-Med.-High Cond. drain connection O.D.

Dimensions Weight

OUTDOOR UNIT MODEL External finish Power supply Max. fuse size (time delay) Min. circuit ampacity Fan motor

Compressor

Refrigerant control Sound level

Defrost method Dimensions Weight

REMOTE CONTROLLER Control voltage (by built-in transformer)

REFRIGERANT PIPING Pipe size (Min. wall thickness)

Connection method Between the indoor

& outdoor units Refrigerant charge (R22) Refrigerating oil (Model)

Btu/h Btu/h Btu/h

W W

A A

F.L.A

A(kW)

CFM CFM

pt./h

(A)

in. in. in. in. Ib.

A A

F.L.A

R.L.A L.R.A

dB(A)

in. in. in. Ib.

in. in.

ft. ft.

lb.

oz.

MSH24WN

22,000 23,600 13,500

2,220 2,230 1,730

9.9 (10.0)

6.8 (5.9)

3.10

MSH24WN

White

115V 60Hz 1[

1.1

0.82 –

431-491-565

402(346)-484(417)-565(487)

7.3

39-43-47

5/8 43-5/16 8-15/16

12-13/16

MUH24WN

Munsell 5Y 7/1

208/230V 60Hz 1[ 3 wires

25 22

0.87

PH33NPBT

C-R 0.84 C-S 2.09

16 58

Linear expansion valve

Reverse cycle

34-1/4 11-5/8 33-1/2

154

Wireless type

12V DC

Not supplied (optional parts)

3/8 (0.0285) 5/8 (0.0315)

Flared

Flared Max. 25 Max. 50

4 Ib. 0 oz.

27.9 (MS32N1)

❈1 ❈3

❈1

❈1 ❈2

❈1

❈1 ❈2

Cooling Heating 47 Heating 17 Cooling Heating 47 Heating 17 Cooling Heating Heating

HEAT Dry COOL Dry(Wet)

W D H

Model Winding resistance (at 68˚F) Ω

W D H

Liquid Gas Indoor Outdoor Height difference Piping length

❈1

Cooling Heating

Maximum Minimum Maximum Minimum

Indoor intake air temperature

95˚FDB, 71˚FWB 67˚FDB, 57˚FWB 80˚FDB, 67˚FWB 70˚FDB, 60˚FWB

Outdoor intake air temperature

115˚FDB

67˚FDB 75˚FDB, 65˚FWB 17˚FDB, 15˚FWB

SPECIFICATION

NOTE : Test conditions are based on ARI 210/240.

❈1 : Rating conditions (cooling) — Indoor : 80˚FDB, 67˚FWB, Outdoor : 95˚FDB, (75˚FWB) ❈2 : (heating) — Indoor : 70˚FDB, 60˚FWB, Outdoor : 17˚FDB, 15˚FWB

❈3 : (cooling) — Indoor : 80˚FDB, 67˚FWB, Outdoor : 82˚FDB, 65˚FWB

Operating Range

(heating) — Indoor : 70˚FDB, 60˚FWB, Outdoor : 47˚FDB, 43˚FWB

Indoor unit

w Max. Height difference 25ft.

Outdoor unit

Refrigerant Piping

Max.length

w Height difference should be within 25ft. regardless of which unit, indoor or outdoor position is high.

Outside

diameter

Minimum

Wall

thickness

Outside

diameter

Minimum

Wall

thickness

MSH24WN MUH24WN

Additional piping

Max. length : ft.

Gas

Piping size : in. Length of connecting pipe : in.

Liquid

Indoor unit

Outdoor unit

Model

Gas :

Liquid :00

Gas :

Liquid :

16-15/16 19-11/16

[ 5/8

[ 3/8

0.0315 0.0285

MAX. REFRIGERANT PIPING LENGTH

MAX. HEIGHT DIFFERENCE

Model

Refrigerant piping length (one way)

1.0

25ft. (std.)

0.954

40ft.

0.923

50ft.

MSH24WN

(208V/ 230V)

Model

Indoor air

Outdoor intake air WB temperature(˚F

)

75 70 65

13.7

14.5

14.9

TPC

1.66

1.61

1.54

17.1

17.7

18.5

TPC

1.95

1.91

1.84

20.4

20.9

21.6

TPC

2.17

2.12

2.06

23.0

23.6

24.3

TPC

2.29

2.23

2.17

23.7

24.3

25.0

TPC

2.32

2.27

2.21

26.9

27.5

28.1

TPC

2.41

2.36

2.32

IDB (˚F)

15 25 35 43 45 55

MSH24WN

NOTE: 1. IDB : Intake air dry-bulb temperature

TC : Total Capacity (x10

Btu/h)

TPC : Total Power Consumption (kW)

2. Above data is for heating operation without any frost.

Model

Indoor air

Outdoor intake air DB temperature(˚F

)

71 67 63

27.0

25.5

24.0

SHC

13.4

16.1

18.3

TPC

1.98

1.86

1.78

25.2

23.8

22.2

SHC

12.5

15.0

17.0

TPC

2.16

2.05

1.96

23.7

22.0

20.7

SHC

11.7

13.9

15.8

TPC

2.33

2.22

2.12

22.0

20.5

18.8

SHC

10.9

12.9

14.4

TPC

2.45

2.35

2.26

20.2

18.8

17.2

SHC

10.1

11.9

13.1

TPC

2.55

2.46

2.35

IWB (˚F)

85 95

105

115

MSH24WN

(208V/ 230V)

NOTE 1. IWB : Intake air wet-bulb temperature

TC : Total Capacity (x10

Btu/h), SHC : Sensible Heat Capacity (x10

Btu/h)

TPC : Total Power Consumption (kW)

2. SHC is based on 80˚F of indoor intake air DB temperature.

DATA

MSH24WN MUH24WN

4-1. PERFORMANCE DATA

1) COOLING CAPACITY

2) COOLING CAPACITY CORRECTIONS

3) HEATING CAPACITY

4-2. PERFORMANCE CURVE

65 70 75 80 85 90 95 100 105 110 115

1.6

1.8

2.0

2.2

2.4

2.6

15 20 25 30 35 40 45 50 55 60

1.6

1.8

2.0

2.2

2.4

2.6

71 67 63

65 70 75

75 70 65

Total power consumption (kW) Total capacity ( ✕10 Btu/h)

Outdoor intake air DB temperature (°F)

Indoor intake air WB temperature (°F)

Indoor intake air WB temperature (

°F)

Cooling

SHF at rating condition = 0.63

= 487CFM = 0.19

Airflow

Bypass Factor

Total power consumption (kW) Total capacity ( ✕10 Btu/h)

Outdoor intake air WB temperature (°F)

Indoor intake air DB temperature (°F)

Heating

= 565CFM

Airflow

208V/230V

MSH24WN MUH24WN

4-3. Condensing pressure

68 70 75 80 85 90 95 100 104(°F)

100

Suction pressure

Outdoor ambient temperature

68 70 75 80 85 90 95 100 104(°F)

140

160

180

200

220

240

260

280

300

(PSIG)

Condensing pressure

Outdoor ambient temperature

Indoor DB temperature (

°F)

86 80 75 70

Indoor DB temperature (°F)

(PSIG)

86 80

75 70

5 101520253035404550556065 70(°F)

140

160

180

200

220

240

260

280

300

320

340

Indoor DB temperature(°F)

75 70 65

75 70

(PSIG)

Condensing pressure

Outdoor ambient temperature

(PSIG)

Suction pressure

Outdoor ambient temperature

5 101520253035404550556065 70(°F)

Indoor DB temperature (

°F)

MSH24WN (Cooling)

Data is based on the condition of indoor humidity 50%. Air flow should be set to High speed.

MSH24WN (Heating)

Data is based on the condition of outdoor humidity 75%. Air flow should be set to High speed. Data is for heating operation without any frost.

4-4. STANDARD OPERATION DATA

MSH24WN

INDOOR UNIT

OUTDOOR UNIT

115V 60Hz 1[, 2 wires

208/230V 60Hz 1[, 2 wires

SIGNAL WIRE 2 wires 12V DC

INDOOR UNIT

OUTDOOR UNIT

208/230V 60Hz 1[, 3 wires

115V 60Hz 1[, 2wires

SIGNAL WIRE 2 wires 12V DC

•Both wirings can be applied.

115V

Disconnect switch

Model

Item

Capacity

Total

Electrical circuit

Refrigerant circuit

Indoor unit

SHF Input Indoor unit Power supply Input Fan motor current Aux. heater current Outdoor unit Power supply Input Comp. current Fan motor current Condensing pressure Suction pressure Discharge temperature Condensing temperature Suction temperature Comp. shell bottom temp Ref. pipe length Refrigerant charge (R22)

Intake air temperature

Discharge air temperature

Fan speed (High) Airflow (High)

Intake air temperature

Outdoor unit

Fan speed Airflow

POWER SUPPLY

Unit

Btu / h

—

A A

A PSIG PSIG

˚F ˚F ˚F ˚F

ft. — ˚F ˚F ˚F ˚F

rpm

CFM

˚F ˚F

rpm

CFM

Cooling

22,000

0.63

2.22

2.149

9.60 / 8.52

257

73 180 116

52 163

1,280

487(Wet)

–

MSH24WN

Heating

23,600

–

2.23

MSH24WN

115V 60Hz 1[

0.071

0.62 –

MUH24WN

208/230V 60Hz 1[

2.159

9.65 / 8.56

0.67/0.71 250

56 185 115

35 167

4 lb. 0 oz.

60 109

–

1,280

565(Dry)

750/820

1,589/1,765

✻ Control voltage

Power supply voltage to serial signal circuit is 12V DC. Voltage between

+ on in-out terminal

- and

block will be 12V DC peak voltage.

4-5. OPERATING RANGE

Indoor unit

Outdoor unit

Rating

115V 60Hz 1[

208/230V 60Hz 1[

Guaranteed Voltage

MSH24WN

MUH24WN

Model

Min. 103V

Max. 127V

115V

Min. 198V Max. 253V

208V

230V

78%

—

Function

Cooling

Heating

Standard temperature

Maximum temperature

Minimum temperature

Maximum humidity

Standard temperature

Maximum temperature

Minimum temperature

DB (˚F)

80 95 67

70 80 70

WB (˚F)

67 71 57

60 67 60

Indoor

DB (˚F)

115

47 75 17

WB (˚F)

— — —

43 65 15

Outdoor

Condition

Intake air temperature

Model

MSH24WN

Mode HEAT

COOL

565 565 487

Air flow

(CFM)

Air speed

(ft./sec.)

Coverage range (ft.)

Function

Dry Dry

Wet

20.1

17.2

34.2

29.4

MSH24WN MUH24WN

Outdoor unit

precharged (up to 25ft.)

4 lb. 0 oz.

25ft.

30ft.

1.61

35ft.

3.22

Refrigerant piping length (one way)

40ft.

4.83

45ft.

6.44

50ft.

8.05

Model

CALCULATION : Xoz. = 1.61/ 5oz./ft. x (Additional Piping Length-25) ft.

(1) POWER SUPPLY

(2) OPERATION

4-6. OUTLET AIR SPEED AND COVERAGE RANGE

● The air coverage range is the figure up to the position where the air speed is 1 ft./sec., when air is blown out horizontally from the unit properly at the High speed position. The coverage range should be used only as a general guideline since it varies according to the size of the room and furniture arranged inside the room.

4-7. ADDITIONAL REFRIGERANT CHARGE (R22(oz.))

6-3/8

3/4

2-5/16

1-7/8

5/16

12-3/8

10-1/161-7/8

1/8

3-7/8

6-13/16

16-5/16 16-5/16

3/168-7/8

8-15/16

9-15/16

31-1/8

2-3/16

42-1/16

43-5/16

12-13/16

Air out

Air in

Insulation [ 1-1/8

Drain hose [5/8 (Connected part O.D)

{

Liquid line [ 3/8 19-11/16 Gas line [ 3/4 16-15/16 Insulation [ 1-15/16 O.D

[ 1-1/4 I.D

Installation plate

Wall hole [ 2-15/16

Wireless remote controller

Installation plate

Indoor unit

OUTLINES AND DIMENSIONS

MSH24WN

INDOOR UNIT

Unit: inch

MUH24WN

Unit: inch

OUTDOOR UNIT

7-9/32

Air intake

Outlet guide installation hole

Handle for moving

17-3/8

7-1/18 20-5/8

1-9/16

Drain hole [1-5/16

19-11/16

Air outlet

34-1/4

11-7/8

20-5/8

2-1/2o7/8 Oval holes

(standard bolt M10)

Air intake

7-9/32

18-7/18

4-1/8

Outdoor Unit-Necessary surrounding clearance

11/16

14-1/4

1-9/16 1-1/16

9/16

Terminal block for power line Terminal block for indoor and outdoor unit connection

Handle for moving

Service panel

Refrigerant-pipe flared

33-1/2

connection [5/8

21-3/4

Refrigerant-pipe flared

17-17/32

2-3/8

1-5/16

Bottom piping hole

1-5/8

connection [3/8

17-23/32

Knock out hole for front piping

(refrigerant,drainage and wiring)

Knock out hole

1-3/4

for right piping (refrigerant,drainage

and wiring)

2-3/8 4-3/4

13/32

Front opening

13/32

19-11/16

1-3/4

2-1/16

Knock out holes for power line 2-[1-1/16

7-7/8

Note:Allow adequate upper clearance

13/32

5-29/32

19-11/16

Service space

Drain hole [1-5/16

Handle for moving

5-7/16

Rear piping hole

3-3/4

Outdoor Unit-Necessary surrounding clearance (Concentrated installation)

13/32

For 10 units or less

The upper side must be open.

7-7/8

39-3/8

2-U-shaped notched holes

Side air intake

Rear fresh air intake

9/32

11-5/8

15/16

Conduit hole

NOTE: Do not wire12V DC and

115V AC in same conduit hole.

15/16

1/2

R1/4

1-5/16

R13/16

2-9/16

11/16

Front right piping holesdetail figures

R13/16

1 max.

3-1/8

Standard bolt length

WIRING DIAGRAM

MSH24WN

INDOOR UNIT

TO OUTDOOR UNIT CONNECTING WIRES 12V DC

FROM OUTDOOR UNIT CONNECTING WIRES POWER

(

)

SUPPLY 115V 1 phase 60Hz

TO OUTDOOR UNIT CONNECTING WIRE

MODEL WIRING DIAGRAM

CN201

1 2 3 4

TAB12

CN 102

DISPLAY P.C.BOARD

ORN

VLT

BLK

RED

CN 151

MV2 MV2 MV1

HIC1

TRANS

F11

101

ELECTRONIC CONTROL P.C. BOARD

RECEIVER P.C.BOARD

w A disconnect may be required by local code.

SYMBOL

C11

F11

HIC1

NOTE:1. About the outdoor side electric wiring, refer to the outdoor unit electric wiring diagram for servicing.

INDOOR FAN CAPACITOR FUSE(3.15A) DC/DC CONVERTER INDOOR FAN MOTOR (INNER PROTECTOR)

2. Use copper conductors only.(For field wiring)

3. Symbols below indicate; : Terminal block, : Connector

MUH24WN

OUTDOOR UNIT

NAME

SYMBOL

MV1

MV2 NR11 RT11

VANE MOTOR(HORIZONTAL) VANE MOTOR(VERTICAL) VARISTOR ROOM TEMPERATURE THERMIST OR

MODEL WIRING DIAGRAM

FROM INDOOR UNIT CONNECTING WIRE

FROM INDOOR UNIT CONNECTING WIRES 12V DC

TO INDOOR UNIT CONNECTING WIRES 115V 1 phase 60Hz

POWER SUPPLY 208/230V 1 phase 60Hz

GROUND

TB2

TB1

RED

GRN/YLW

BLK

RED

NAME NAME

RT61

RT62 RT63

CN661

RED

BLU BLU

DSAR

CN662

X52X62

T61

LEV

CN724

SR61

DEICER P.C.BOARD

A2 A1

52C

NR11

C11

SR141

REMOTE CONTROLLER

SYMBOL

RT12 RT13

SR141

WHT

BLK

3456

BLK

WHT

123

NR61

52C

4 3 2 1

CN112

CN 121

1 3 4

CN211

CN 111

BLK GRY YLW BRN

WHT

RED

RT13 RT12

RT11

INDOOR COIL THERMISTOR(MAIN) INDOOR COIL THERMISTOR(SUB) SOLID STATE RELAY TERMINAL BLOCK

ORN

RED

ORN

CN711

X62

COM

X52

COM

F61

CN730

ORN VLT BLU RED

CN721

TAB52

WHT

RED BLK

BLK

1 2 3

1 3 5 7

21S4

BLK

BLU

SG79J618H02

SYMBOL

C1 C2

DSAR

F61

LEV

MC MF

NOTE:1. About the indoor side electric wiring, refer to the indoor unit electric wiring diagram for servicing.

COMPRESSOR CAPACITOR OUTDOOR FAN CAPACITOR SURGE ABSORBER FUSE(3.15A) EXPANSION VALVE COIL COMPRESSOR(INNER PROTECTOR) OUTDOOR FAN MOTOR(INNER PROTECTOR)

2. Use copper conductors only.(For field wiring)

3. Symbols below indicate; : Terminal block, : Connector

NAME

SYMBOL

NR61 RT61 RT62 RT63 SR61

TB1 TB2

NAME NAME VARISTOR DEFROST THERMISTOR

DISCHARGE TEMPERATURE THERMIST OR

AMBIENT TEMPERA TURE THERMIST OR SOLID STATE RELAY TERMINAL BLOCK TERMINAL BLOCK

SYMBOL

T61 X52 X62

21S4

52C

TRANSFORMER

COMPRESSOR AUXILIARY RELAY R.V. COIL RELAY R.V. COIL

COMPRESSOR CONTACTOR

SG79J604H02

REFRIGERANT SYSTEM DIAGRAM

Unit: inch

MSH24WN MUH24WN

INDOOR UNIT

Indoor heat exchanger

Room temperature thermistor RT11

Indoor coil thermistor RT12(main)

Indoor coil thermistor RT13(sub)

Strainer

#50

Refrigerant pipe [5/8 (with heat insulator)

Flared connection

Refrigerant pipe [3/8 (with heat insulator)

4-way valve

Muffler

Stop valve (with service port)

FUSIBLE PLUG

SERVICE PORT

Accumulator

Strainer

#100

Stop valve

Strainer

#100

SERVICE

Discharge thermistor RT62

Compressor

Capillary tube

Check

O.D. 0.17✕I.D. 0.12✕11-13/16

valve

Capillary tube O.D. 0.17✕I.D. 0.12✕1-31/32

LEV

PORT

Strainer

#100

OUTDOOR UNIT

Outdoor heat

Defrost thermistor RT61

Refrigerant flow in cooling Refrigerant flow in heating

exchanger

Ambient temperature thermistor RT63

R.V. coil heating ON cooling OFF

MICROPROCESSOR CONTROL8

lighted not lighted

Approx. 4-F or more

Difference between target temperature and room temperature

Approx. 4-F or less

This shows that the air conditioner is operating to reach the target temperature. Please wait unit the target temperature is obtained.

This shows that the room temperature is approaching the target temperature.

Operation stateIndication

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.

ON/OFF

FAN

TOO

WARM

TOO

COOL

VANE

MODE

STOP

START

HR.

MIN.

WIDE VANE

LONG

I FEEL

COOL

HEAT

DRY

CLOCK

RESET CLOCK

OPERATION SELECT button

FAN SPEED CONTROL button

OFF-TIMER button

HR. button

MIN. button

(TIME SET button)

ON-TIMER button

RESET button

VANE button

(Horizontal vane button)

CLOCK SET button

LONG button

WIDE VANE button

(Vertical vane button)

ON/OFF

TOO COOL

TOO

WARM

Signal transmitting section

Operation display section

OPERATE /STOP

(ON /OFF)button

TEMPERATURE buttons

WIRELESS REMOTE CONTROLLER

MSH24WN MUH24WN

Once the operation mode is set, the same operation mode can be repeated by simply turning the OPERATE/STOP (ON/OFF) button 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.

8-1. “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 the OPERA-

TION SELECT button.

(3) The operation mode is determined by the room tem-

perature at start-up of the operation.

Initial room temperature

77-F or more

73-F

77-F

less than 73-F

"I FEEL CONTROL"

• Once the mode is fixed, the mode does not change by room temperature afterwards.

• Under the ON-TIMER ( ) operation, mode is determined according to the room temperature at the set time the operation starts.

• 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.

Example Previous operation

COOL mode of “I FEEL CONTROL” or COOL mode

Mode

COOL mode of

DRY mode of

HEAT mode of

Restart

COOL mode of “I FEEL CONTROL”

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.

Example

Previous operation

COOL mode of “I FEEL CONTROL”

or COOL mode

Restart

COOL or DRY or HEAT mode of “I FEEL CONTROL” that determined by room temperature at start-up of the operation.

Model

COOL mode of

"I FEEL CONTROL"

DRY mode of

"I FEEL CONTROL"

HEAT mode of

"I FEEL CONTROL"

Initial room temperature Initial set temperature

79-F

79-F or more

77-F to 79-F

less than 73-F

73-F to 77-F

75-F

Initial room temperature

minus 4-F

Initial room temperature

minus 4-F

❈1

(4) The initial set temperature is decided by the initial room temperature.

TOO

COOL

TOO

WARM

Difference between room temperature and set temperature during operation

2deg. 3deg.

4deg.

❈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 2~4 degrees(°F)

8-1-1. COOL mode of “I FEEL CONTROL”

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.

Room temperature minus set temperature : 3 degrees or more Room temperature minus set temperature : Between 2 and 3 degrees Room temperature minus set temperature : less than 2 degree

2. Coil frost prevention

① Temperature control

When the indoor coil thermistor RT12 or RT13 reads 30°F or below 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 or RT13 still reads below 30°F this mode prolonged until the RT12 or RT13 still reads over 30°F.

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 79°F.

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. However, when two of the above conditions (b.and c.) are satisfied again. Time accumulation is resumed.

…

To lower the set temperature 2~4 degrees(°F)

Initial temperature difference Fan Speed

·····························High

··················Med.

·····························

Low

Operation chart

Example

Compressor Outdoor fan

Indoor fan

3. Discharge temperature protection

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 248°F 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 212°F or less, the compressor is turned ON.

OFF

(continuously at set speed)

OFF

8-1-2. 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.

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. 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 from initial room temperature. Indoor fan and outdoor fan operate in the same cycle as the compressor.

•When the room temperature is 73°F 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.

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

OFF

Indoor fan

Outdoor fan Compressor

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, it’s speed becomes Low.

OFF

8 min.

OFF

3 min.

OFF

1 min.4 min.

8-1-3. HEAT mode of “I FEEL CONTROL”

Difference between room temperature and set temperature during operation

2deg. 3deg.

7deg.

4deg.

Released

Cold Air Prevention

64F- 72F-

Fan speed Set speed Very Low or stop

1. Indoor fan speed control

(1) In AUTO the fan speed is as follows.

Set temperature minus room temperature: 4 degrees or more················································· High Set temperature minus room temperature: Between 2 and 4 degrees····································· Med. Set temperature minus room temperature: less than 2 degree················································· Low

(2) Cold air prevention control

The fan runs at set speed when the indoor coil thermistor RT12 temperature exceeds 72°F. The fan operates Low when the temperature of indoor coil thermistor RT12 is below 64°F. But the fan stops when the indoor fan operates at Very Low and the room temperature is 59°F or less.

Initial temperature difference Fan speed

Indoor coil thermistor RT12 temperature

NOTE : If the temperature of RT12 reads from 64°F to 72°F 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 thermistor RT12 temperature to blow out warm air. After releasing of cold air prevention, when the indoor coil thermistor RT12 temperature is 99°F 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 thermistor RT12 temperature is less than 99°F, 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 72°F or more.

2. High pressure protection

During heating operation, the outdoor fan and the compressor are controlled by the temperature of indoor coil thermistor RT12 for excess rise protection of compressor discharge pressure.

• Outdoor fan When the temperature of indoor coil thermistor RT12 goes to 131°F or more, the outdoor fan is turned OFF. When the temperature of indoor coil thermistor RT12 becomes to 126°F or less, the outdoor fan is turned ON.

• Compressor When the temperature of indoor coil thermistor RT12 goes to 167°F or more, the compressor is turned OFF. 3 minutes after the compressor is turned OFF and if the temperature of indoor coil thermistor RT12 becomes 167°F or

less, the compressor is turned ON.

NOTE : During the high pressure protection and for 10 seconds after high pressure protection, defrosting of outdoor heat

exchanger is not detected by the defrost thermistor RT61.

3. Discharge temperature protection

Discharge temperature protection is as same as during COOL mode of “I FEEL CONTROL”.

4. Defrosting

Defrosting of outdoor heat exchanger is controlled by deicer P.C. board, with detection by the defrost thermistor RT61.

(1) Starting conditions of defrost

When all conditions of a) ~ c) are satisfied, the defrosting operation starts.

a) Under the heat operation, the compressor cumulative operation time exceeds 40 minutes without the defrosting opera-

tion working. b) The defrost thermistor RT61 reads 27°F or less. c) After releasing the high pressure protection 4 minutes and 10 seconds have elapsed.

(2) Releasing conditions of defrost

When the condition d) or e) is satisfied, the defrosting operation stops.

d) The defrost thermistor RT61 reads 56°F or more. e) The defrosting time exceeds 10 minutes.

(3) Defrosting time chart

Defrost thermistor RT61 56°F or more 27°F or less

Outdoor 52C contactor (Compressor)

X62 (R.V. coil)

SR61 Outdoor fan

Defrost counter

Indoor fan

ON OFF

ON Very Low OFF

30 sec.

NOTE1

15 sec.

30 sec.

5 sec.

Max 10 min.

Indoor vane

Horizontal

Set position

NOTE1 • When the indoor coil thermistor RT12 reads above 64°F, indoor fan operates at Very Low for 30 seconds.

• When the indoor coil thermistor RT12 reads 64°F or less, the indoor fan stops.

5. R.V. coil control

50 59 68 77 86 95

-F

Heating · · · · · ON Cooling · · · · · OFF Dry · · · · · · · · OFF NOTE: The 4-way valve reverses for 5 seconds right before start-up of the compressor.

Compressor

R.V. coil

Outdoor fan

8-2. 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 the OPERATION SELECT

button.

(3) Press TEMPERATURE buttons.

(TOO WARM or TOO COOL button) to select the desired temperature. The setting range is 59 ~ 89°F. ✻ 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”.

8-3. 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 the OPERATION SELECT

button.

(3) The microprocessor reads the room temperature

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 tem-

perature is 55°F or below.

ON OFF

(COOL / DRY)

5 sec.

(HEAT)

5 sec.

ON OFF

8-4. HEAT ( ) OPERATION

(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 59 ~ 89°F. (4) Indoor fan speed control, high pressure protection, defrosting, R.V. coil control are the same as HEAT mode of “I FEEL

CONTROL”.

8-5. 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 feed back 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.

Rotational frequency

High

Med.

Low

(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. (Refer to page 33.)

High

time

8-6. AUTO VANE OPERATION

1. Horizontal vane

(1) Vane motor drive

This model is 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 changes as follows by pressing the VANE button.

AUTO

(3) Positioning

The vane is once pressed to the vane stopper below 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.

Horizontal

34 5

Middle Downward Swing

(4) VANE AUTO ( ) mode

In VANE AUTO mode, the microprocessor automatically determines the vane angle and operation to make the optimum room-temperature distribution.

① In COOL and DRY operation

➁ In HEAT operation

Vane angle is fixed to Angle 1.

Vane angle is fixed to Angle 4.

COOL / DRY HEAT

Fan speed : Faster Solid arrow : When the LONG mode is used. Dotted arrow : When the LONG mode is not used.

Air flow direction Air flow blowing range

45SWING

(5) STOP (operation OFF) and ON-TIMER standby.

Released

Cold Air Prevention

75F- 82F-

Angle 1

Horizontal vane

Set position

When the following cases occur, the horizontal vane returns to the closed position. (a) When the OPERATE/STOP (ON/OFF) button is pressed (POWER OFF). (b) When the operation is stopped by the emergency operation. (c) When the ON-TIMER is on standby.

(6) 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.

(7) SWING MODE ( )

By selecting SWING mode with the VANE button, the horizontal vane swings vertically. The remote controller displays “”.

(8) Cold air prevention in HEAT operation

When any of the following conditions occurs in HEAT operation, the vane angle changes to Angle 1 automatically to prevent cold air blowing on users.

① Compressor is not operating. ➁ Defrosting is performed. ➂ Indoor coil thermistor RT12 reads 75°F or below. ➃ Indoor coil thermistor RT12 temperature is raising from 75°F or below, but it does not exceed 82°F.

Indoor coil thermistor RT12 temperature

NOTE: If the temperature of RT12 reads from 75°F to 82°F at the air conditioner starting, this control works.

(9) LONG MODE ( )

By pressing the LONG button fan speed becomes faster than setting fan speed on the remote controller, and the horizontal vane moves to the position for LONG mode. The remote controller displays “ ”. LONG mode is cancelled

when the LONG button is pressed once again or the VANE button is pressed.

• In the following example, the vertical vane is set to (front.).

2. Vertical vane

(1) Vane motor drive

This model is equipped with a stepping motor for the vertical vane. The rotating direction, speed, and angle of the motor are controlled by pulse signals (approx. 12V) transmitted from microprocessor.

(2) The vertical vane angle and mode change as follows by pressing the WIDE VANE button.

(3) Positioning

COOL and DRY

HEAT

About 100-

About 150-

Horizontal AIR FLOW blowing range

The vane is once pressed to the vane stopper to confirm the standard position and then set to the desired angle. Confirming of standard position is performed under following conditions. (a) When the OPERATE/STOP(ON/OFF) button is pressed (POWER ON/OFF). (b) When the SWING is started or finished. (c) When the power supply turns ON.

(4) SWING MODE ( )

By selecting SWING mode with the WIDE VANE button, the vertical vane swings horizontally. The remote controller displays “ ”. The vane moves right and left in the width of Angle 4 repeatedly.

(5) WIDE MODE ( )

By selecting WIDE mode with the WIDE VANE button, indoor fan speed becomes faster than setting fan speed on the remote controller (W). The remote controller displays “ ”. NOTE : The position of vane angle 3, angle 4 and angle 5 are different in COOL operation and HEAT operation.

W Indoor fan speed becomes faster than setting fan speed on the remote controller even when or is

selected.

8-7. 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 TIMER CONTROL button to select the operation.

“ON-TIMER” button... AUTO START operation (ON timer) “OFF-TIMER” button... AUTO STOP operation (OFF timer)

(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 the 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.

• Apower failure occurs.

•The circuit breaker functions.

2. Cancel

TIMER setting can be cancelled with the ON/OFF TIMER buttons. To cancel the ON timer, press the “ON-TIMER” button. To cancel the OFF timer, press the “OFF-TIMER” button. TIMER is cancelled and the display of set time disappears.

Press once <Cool>

Press again <Heat>

Press once again <Stop>

OPERATION INDICATOR lamp

• The following indication applies regardless of shape of the indicator.

EMERGENCY OPERATION switch

PROGRAM TIMER

• The OFF timer and ON timer can be used in combination.

• “ ” and “ ” display shows the order of the OFF timer and ON timer operation.

(Example 1) The current time is 8:00 PM.

The unit turns off at 11:00 PM, and on at 6:00 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.

8-8. EMERGENCY-TEST OPERATION

In case of test run operation or emergency operation, use the 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 the 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 MODE with a set temperature of 75°F. The fan speed shifts to Med. speed. The coil frost prevention works even in emergency operation, and defrosting too.

In the test run or emergency operation, the horizontal vane operates in VANE AUTO ( ) mode. Emergency operation continues until the EMERGENCY OPERATION switch is pressed once or twice or the unit receives any signal from the remote controller. In case of latter normal operation will start.

NOTE : Do not press the EMERGENCY OPERATION switch during normal operation.

8-9. LEV control

Controlled range

Basic specification

Minimum : 54 pulse, Maximum : 500 pulse

Drive speed

30 ~ 90 pulse / second

Opening set

Stop of indoor unit

Opening in stop : 150 pulse ➔ LEV opening is set to becomes 500 pulse after 3 minutes passed.

Remote controller ON

LEV positioning (LEV is closed completely at once)

Power ON (Breaker ON)

LEV is positioned. However, afterwards, LEV is not positioned at the first remote controller ON.

Approximate for 2 minutes since compressor has started.

Opening is set by the initial opening. (Initial opening is set according to each operation modes and outer temperature conditions.)

From approximate 2 minutes to approximate 13 minutes (for 11 minutes) since compressor has started.

Opening is set by standard opening. (Standard opening is set according to each operation modes and outer temperature conditions.)

After 13 minutes passed since compressor has started.

LEV opening is corrected to be once every 2 minutes so that discharge temperature becomes the target discharge temperature. (When the discharge temperature is lower than target one : LEV is corrected in closed direction, when the discharge temperature is higher than target one : LEV is corrected in opening direction.)

At thermostat OFF

Opening in stop : 150 pulse ➔ LEV is set to the initial opening after about 3 minutes passed.

At thermostat ON

Same as the starting of compressor operation

At remote controller OFF

Opening in stop : 150 pulse ➔ LEV is set so that the opening is opened completely at the speed of 4 pulse every 5 seconds in opening after about 3 minutes passed.

General operation

The setting is always in opening direction. (To close the LEV, it is closed to the pulse smaller than the one which is set finally. Then the LEV is opened to the final setting pulse.)

Rank

Ta (F-) more than Tb+18 Tb+9 to Tb+18 Tb+4 to Tb+9 Tb-4 to Tb+4 Tb-9 to Tb-4 Tb-18 to Tb-9 less than Tb-18

100 pulse or less

(Pulse)

Cooling / Heating

5 2 1 0

-1

-2

-5

NOTE : Discharge temperature : Ta, Target discharge temperature : Tb

100 pulse or more

(Pulse)

Cooling / Heating

20 10

2 0

-2

-5

-10

Opening immediately before having stopped last time

LEV (Expansion valve) is controlled by “Thermostat ON” commands given from the unit.

(1) LEV opening correction by discharge temperature

The LEV opening is corrected according to the temperature difference between target discharge temperature (Tb) and actual discharge temperature (Ta). 1 The LEV correction is used properly for two kinds according to the LEV opening status at operation off.

2 When the temperature difference RT between indoor coil thermistor (main) RT12 and indoor coil thermistor (sub)

Ta (F-)

more than Tb+18 Tb+9 to Tb+18 Tb+4 to Tb+9 Tb-4 to Tb+4 Tb-9 to Tb-4 Tb-18 to Tb-9 less than Tb-18

less than 4deg.

(Pulse)

20 10

2 0

-2

-5

-10

NOTE : Discharge temperature : Ta, Target discharge temperature : Tb

6deg. or more

(Pulse)

60 20 10

-2

-5

-10

4deg. or more and less than 6deg.

(Pulse)

60 20 10

-2

-5

-10

Tb (-F) HEAT COOL (Normal) COOL

( RT is less than 4deg., or RT is 4deg. or more and less than 6deg..)

COOL ( RT is 6deg. or more.)

NOTE : Target discharge temperature : Tb

180 176 144 136

Operation mode

NOTE : Opening increases and decreases to be in the target discharge temperature during operation.

Opening completely

Positioning

Power ON

Initial opening

Standard opening

Remote controller ON

➔

Operation

Thermostat OFF

Standard opening

Thermostat ON

Opening in stop

Initial opening

Operation

Opening in stop

Remote controller OFF

Opening completely

Remote controller ON

➔

Positioning

Initial opening

Standard opening

Operation

Time

LEV opening

Open

RT13 in the indoor unit is 4deg. or more for a fixed time at cool or dry operation, the target discharge temperature is changed. After the temperature is changed, when temperature difference RT is 6deg. or more, the target

temperature is changed again. The LEV opening is controlled based on the changed target discharge temperature and the temperature difference RT.

The target discharge temperature (Tb) is set according to the operation mode or the unit status as follows.

NOTE : When the discharge temperature (Ta) is 122°F or less on the cool operation, or is 120°F or less on heat operation,

LEV opening is set in 54 pulse. When this state continues for 20 minutes, the compressor is stopped and restarts in 3 minutes. When the compressor is stopped, the indoor unit indicates the abnormality of refrigerant system and stops. (OPERATION INDICATOR lamp is 10-time flashing on and off.)

(2) LEV time chart

SERVICE FUNCTIONS9

MSH24WN MUH24WN

9-1. COMPULSORY DEFROSTING MODE FOR SERVICE

By short circuit of the connector JPG1 and R871 on the outdoor deicer P.C. board, defrosting mode can be accomplished regardless of the defrost interval restriction. Defrost thermistor RT61 must read below 27°F. (Refer to page 42.)

9-2. CHANGE IN DEFROST SETTING

<JRF> When the JRF wire of the deicer P.C. board is cut, the defrost interval time is changed. <JRG> When the JRG wire of the deicer P.C. board is cut, the defrost temperature is changed. (Refer to page 42.)

Model

Jumper wire

JRF

Defrost interval time changes from 40 minutes to 15minutes.

Change point

MUH24WN

JRG

Defrost start temperature does not change (27˚F). Defrost finish temperature changes from 56˚F to 59˚F.

9-3. TIMER SHORT MODE

For service, set time can be shortened by short circuit of JPG and JPS the electronic control P.C. board. The time will be shortened as follows. (Refer to page 41.)

Set time : 1 minute ➔ 1-second Set time : 3 minute ➔ 3-second (It takes 3 minutes for the compressor to start operation. However, the starting time is

shortened by short circuit of JPG and JPS.)

9-4. P.C. BOARD MODIFICATION FOR INDIVIDUAL OPERATION

A maximum of 4 indoor units with wireless remote controllers can be used in a room. In this case, to operate each indoor unit individually by each remote controller, P.C. boards of remote controller must be modified according to the indoor unit number.

How to modify the remote controller P.C. board

Remove batteries before modification. The board has a print as shown below :

The P.C. board has the print “J1” and “J2”. Solder “J1” and “J2” according to the number of indoor unit as shown in Table 1. After modification, press the RESET button.

NOTE : For remodelling, take out the

batteries and press the OPERATE/STOP(ON/OFF)button twice or 3 times at first. After finish remodelling, put back the batteries then press the RESET button.

Table 1

No. 1 unit No. 2 unit No. 3 unit No. 4 unit

1 unit operation No modification

– – –

2 units operation

Same as at left

Solder J1

– –

3 units operation

Same as at left Same as at left

Solder J2

–

4 units operation

Same as at left Same as at left Same as at left

Solder both J1 and J2

JR07

IC152

CN151

CN112

CN111

CN121

SW1

IC101

RA102

C11

CN201

CN211

TAB12

How to set the remote controller exclusively for particular indoor unit

After you turn the breaker ON, the first remote controller that sends the signal to the indoor unit will be regarded as the remote controller for the indoor unit. The indoor unit will only accepts the signal from the remote controller that has been assigned to the indoor unit once they are set. The setting will be cancelled if the breaker has turned off, or the power supply has shut down. Please conduct the above setting once again after the power has restored.

9-5. AUTO RESTART FUNCTION

When the indoor unit is controlled with the remote controller, the operation mode, the set temperature, and the fan speed are memorized by the indoor electronic control P.C. board. When the main power is turned off and then turned back on, the unit restarts automatically in the memorized set conditions approximately after 3 minutes.

How to release “AUTO RESTART FUNCTION”

1 Turn off the main power for the unit. 2 Pull out the indoor electronic control P.C. board and the display P.C.board. (Refer to page 44.) 3 Solder the Jumper wire or the Resistor 220Ω to the JR07 on the indoor electronic control P.C.board.

(Refer to page 41.)

Operation

1 If the main power (115V AC) has been cut, the operation settings

remain.

2 After the power is restored, the unit restarts automatically according to

the memory.(However, it takes at least 3 minutes for the compressor to start running.)

NOTE:

•The operation settings are memorized when 10 seconds have passed after the indoor unit was operated with the remote

controller.

•If the main power is turned off or a power failure occurs while AUTO START/STOP timer is active, the timer setting is

cancelled.

•If the unit has been off with the remote controller before power failure, the auto restart function does not work as the

power button of the remote controller is off.

•To prevent breaker off due to the rush of starting current, systematize other home appliances not to turn on at the same

time.

•When some air conditioners are connected to the same supply system, if they are operated before power failure, the

starting current of all the compressors may flow simultaneously at restart. Therefore, special counter-measures are required to prevent the main voltage-drop or the rush of the starting current by adding to the system that allows the units to start one by one. (time delay)

TROUBLESHOOTING10

Lead wiring

Housing point

RESET button

Insert the negative pole of the batteries first. Check if the polarity of the batteries are correct.

MSH24WN MUH24WN

10-1. Cautions on troubleshooting

1. Before troubleshooting, check the following:

1) Check the power supply voltage.

2) Check the indoor/outdoor connecting wire for mis-wiring.

2. Take care the following during servicing.

1) Before servicing the air conditioner, first be sure to turn off the remote controller to stop the unit, and then after confirming the horizontal vane is closed, turn off the breaker and / or disconnect the power plug.

2) Be sure to turn OFF the power supply before removing the front panel, the cabinet, the top panel, and the electronic control P.C. board.

3) When removing the electronic control P.C. board, hold the edge of the board with care NOT to apply stress on the components.

4) When connecting or disconnecting the connectors, hold the housing of the connector. DO NOT pull the lead wires.

3. Troubleshooting procedure

1) First, check if the OPERATION INDICATOR lamp on the indoor unit is flashing on and off to indicate an abnormality.

To make sure, check how many times the abnormality indication is flashing on and off before starting service work.

2) Before servicing check that the connector and terminal are connected properly.

3) If the electronic control P.C. board is supposed to be defective, check the copper foil pattern for disconnection and the

components for bursting and discoloration.

4) When troubleshooting, refer to the flow chart on page 32 and the check table on page 33.

4. How to replace batteries

Weak batteries may cause the remote controller malfunction. In this case, the remote controller can be repaired only by the battery replacement. To operate the remote controller normally, replace the batteries in the following order. This remote controller has the RESET button. After refilling new batteries, press the RESET button with tip end of ball point pen or the like, and then use the remote controller.

1 Remove the front lid and insert batteries.

Then reattach the front lid.

NOTE : If the RESET button is not pressed, the remote controller may not operate correctly.

2 Press the RESET button.

10-2. Instruction of troubleshooting

Start

Indoor unit operates. Outdoor unit doesn't operate.

Indoor unit doesn't receive the signal from remote controller.

Indoor unit operates. Outdoor unit doesn't operate normally.

OPERATION INDICATOR lamp on the indoor unit is flashing on and off.

Outdoor unit operates in only Test Run operation.

Outdoor unit doesn't operate even in Test Run operation.

Indoor unit operates, when the EMERGENCY OPERATION switch is pressed.

Indoor unit doesn't operate, when the EMERGENCY OPERATION switch is pressed.

Check room temperature thermistor. Refer to "Test point diagram and voltage" on page 41.

Refer to D "Check of outdoor unit" on page 37.

Refer to B "Check of remote controller and receiver P.C. board" on page 35.

Flash on and off at 0.5second intervals Cause: Indoor/ Outdoor unit

• Mis-wiring

2-time flash Cause: Indoor unit

• Trouble of room temp erature/ indoor coil thermistor

3-time flash Cause: Indoor unit

• Trouble of indoor fan motor

6-time flash Cause: Outdoor unit

• Trouble of thermistor in outdoor unit

7-time flash Cause: Outdoor unit

• Trouble of outdoor control system

Check room temperature thermistor and indoor coil thermistor. Refer to "Test point diagram and voltage" on page 41.

Refer to A "Check of indoor fan motor" on page 35.

Refer to I "Check of outdoor thermistor" on page 40.

Replace the deicer P.C. board.

10-time flash Cause: Outdoor unit

• Trouble of low discharge temperature protection

Refer to H "Check of LEV" on page 40.

4-time flash Cause: Indoor unit

• Trouble of indoor unit control system

Replace the indoor electronic control P.C. board.

1. Check indoor / outdoor connecting wire.

2. Refer to C "Check of indoor electronic control P.C. board" on page 36.

Outdoor unit doesn't stop even if indoor unit stops.

Unit doesn't operate normal operation in COOL or HEAT mode.

Refer to E "Check of outdoor unit" on page 38.

Refer to F "Check of R.V. coil" on page 38.

Refer to G "How to check mis-wiring (When outdoor unit doesn't operate)" on page 39.

Operation Indicator

flashing

No.

SymptomOperation indicator lamp Detection method

Checkpoint

0.5-second ON

0.5-second OFF

Mis-Wiring

Outdoor thermistor

Outdoor control system

Indoor coil thermistor

3 minutes after power supply turns ON, when serial signal is not received.

<Thermistor short> Thermistors are abnormal when they short after compressor start-up. <Thermistor open> Thermistors are abnormal when they open after compressor start-up. However, discharge temperature thermistor is abnormal when open circuit is detected more than 10 minutes after compressor start-up.

When it cannot properly read data in the nonvolatile memory of the deicer P.C. board, outdoor unit stops.

• Shortage of refrigerant

• Replace the deicer P.C. board. Refer to I "Check of outdoor

thermistor" on page 40.

• Replace the deicer P.C. board.

• Refer to G "How to check

mis-wiring" on page 39.

Indoor fan

motor

Low discharge temperature protection

When discharge temperature has been 122-F or less on cool operation, or has been 120-F or

less on heat operation for 20 minutes.

Abnormal

point

Outdoor unit does not operate.

Room temperature thermistor

2-time flash

2.5-second OFF

Detect Indoor coil/room temperature thermistor short or open circuit every 8 seconds during operation.

• Refer to the characteristics of main indoor coil thermistor, sub indoor coil thermistor, and room temperature thermistor on page 41.

3-time flash

2.5-second OFF

Indoor fan repeats 12 seconds ON and 3 minutes OFF. When the indoor fan breaks, the fan keeps stopping.

When rotational frequency feedback signal is not emitting during 12-second indoor fan operation.

• Refer to A "Check of indoor fan motor" on page 35.

4-time flash

2.5-second OFF

Indoor control system

When it cannot properly read data in the nonvolatile memory of the indoor electronic control P.C. board.

Outdoor unit does not operate.

• Replace the indoor electronic control P.C. board.

6-time flash

2.5-second OFF

• Refer to H "Check of LEV" on page 40.

• Check refrigerant circuit and refrigerant amount.

Outdoor unit does not operate.

7-time flash

2.5-second OFF

10-time flash

2.5-second OFF

1. Troubleshooting check table

• The following indication applies regardless of shape of the indicator.

· Flashing of the OPERATION INDICATOR lamp (on the left-hand side) indicates possible abnormalities.

· The OPERATION INDICATOR lamp (on the left-hand side) is lighting during normal operation.

Before taking measures, make sure that the symptom reappears, for accurate troubleshooting. Self check table

NOTE : When the indoor unit has started operation and the above detection method has detected an abnormality (the first

detection after the power ON), the indoor electronic control P.C. board turns OFF the indoor fan motor with the OPERATION INDICATOR lamp flashing.

2. Trouble criterion of main parts

Part name FigureCheck method and criterion

Measure the resistance between the terminals with a tester. (Part temperature 14˚F ~ 104˚F)

Compressor(MC) INNER

PROTECTOR 320i 9-F OPEN 198i20-F CLOSE

Indoor fan motor(MF) INNER

PROTECTOR 275i 9-F OPEN 187i27-F CLOSE

Normal

Terminal

C – R

C – S

0.74 " ~ 0.91 "

1.84 " ~ 2.26 "

Abnormal

Open or

short-circuit

Measure the resistance with a tester. (Part temperature 14˚F ~ 104˚F)

Color of lead wire

WHT – BLK BLK – RED

Abnormal

Open or

short-circuit

Normal 35 " ~ 39 " 65 " ~ 71 "

Measure the resistance with a tester. (Part temperature 50˚F ~ 86˚F)

Normal

8 k" ~ 20 k"

Abnormal

Open or short-circuit

Room temperature thermistor(RT11)

Indoor coil thermistor (RT12(main), RT13(sub))

Discharge temperature thermistor(RT62)

Ambient temperature thermistor(RT63)

Outdoor fan motor(MF) INNER

PROTECTOR 293i14-F OPEN 190i27-F CLOSE

Horizontal vane motor(MV1) Vertical vane motor(MV2)

R.V. coil(21S4)

LEV(Expansion valve)

Measure the resistance with a tester. Before measurement, hold the thermistor with your hands to warm it up. (Part temperature 32˚F ~ 104˚F)

Normal

120 k" ~ 800k"

Abnormal

Open or short-circuit

Normal

5 k" ~ 60 k"

Abnormal

Open or short-circuit

Motor part

Sensor part

Measure the resistance between the terminals with a tester. (Part temperature 50˚F ~ 86˚F)

Measure the voltage power ON.

Color of lead wire

BRN – YLW

YLW – GRY

Abnormal

Remain 0V or 5V

Normal

4.5 ~ 5.5V

(When fan revolved one time)

0V➔5V➔0V

(Approx.)

Measure the resistance between the terminals with a tester. (Part temperature 14˚F ~ 104˚F)

Color of lead wire

WHT – BLK

BLK – RED

Abnormal

Open or

short-circuit

Normal 51 " ~ 62 " 50 " ~ 61 "

Normal

282" ~ 306 "

Abnormal

Open or short-circuit

Measure the resistance between the terminal with a tester. (Part temperature 50°F ~ 86°F)

Measure the resistance between the terminals with a tester. (Part temperature 14˚F ~ 104˚F)

Normal

2.673 k" ~ 3.268 k"

Abnormal

Open or short-circuit

Color of lead wire

WHT – RED RED – ORN YLW – BRN

BRN – BLU

Abnormal

Open or

short-circuit

Normal

30.3 " ~ 37.0 "

Measure the resistance with a tester. (Part temperature : 14˚F ~ 104˚F)

Measure the resistance with a tester. (Part temperature 14˚F ~ 104˚F)

Normal

5 k" ~ 60 k"

Abnormal

Open or short-circuit

Defrost thermistor (RT61)

RED

BLK

WHT

MAINAUX.

1 2 3

RED

BLK

MAIN

AUX.

YLW GRY BRN

WHT

1 2 3

RED

AUX.

MAIN

ORN

BLK

WHT

RED

YLW BRN

ORN

GRN

ROTOR

LEV

WHT

RED1 ORN4

YLW5

BRN2

BLU3

:INNER PROTECTOR

MSH24WN MUH24WN

When OPERATION INDICATOR lamp flashes 3-time. Indoor fan motor doesn’t operate.

Check of indoor fan motor

Turn OFF the power supply. Check connector CN211 visually.

Reconnect the lead wires.

Disconnect lead wires from connector CN211 on the indoor electronic control P.C. board. Measure resistance between lead wires No.3 and No.4 and then No.1 and No.4.

Are lead wires connected?

Is resistance 0 (short circuit) or ∞ (open circuit)?

Repair or replace the indoor fan motor.

Yes

Yes ( 0 or ∞ )

Is soldered point of the connector correctly soldered?

Yes

Turn ON the power supply. Stop it if the unit operate. Insert screwdriver into air outlet to rotate indoor fan motor slowly for 1 revolution or over, and measure

(others)

voltage between No.2(+) and No.3(-) on CN121.

Does voltage repeat 0V DC and 5V DC?

Replace the indoor electronic control P.C. board.

Resolder it.

Yes

Indoor unit operates by pressing the EMERGENCY OPERATION switch, but doesn’t operate with the remote controller.

Check of remote controller and receiver P.C. board

w Check if the remote controller is exclusive for this air conditioner.

Switch on the remote controller.

Is LCD display on the the remote controller visible?

Yes

No (not clear)

Replace the batteries.(Refer to page 31.)

Remove the batteries, then set them back and press the RESET button. Check if the unit operates with the remote controller.

Does the unit operate with the remote controller?

Yes

Turn on a radio to AM and press switch on the remote controller.

Is noise heard from radio?

Yes

Are there any fluorescent lights of inverter or rapid-start type within the range of 1m?

Measure the voltage between receiver P.C. board connector CN301 No.1(+) and No.3(-) when the remote

controller button is pressed.

Is the voltage approx. 4V DC?

No(5V or 0V DC)

Replace the receiver P.C. board.

Yes

Replace the remote controller.

● Reinstall the unit away from lights.

● Attach a filter on receiving part.

Replace the indoor electronic control P.C. board.

The unit doesn’t operate with the remote controller. Also, the OPERATION INDICATOR lamp doesn’t light up by pressing the EMERGENCY OPERATION switch.

Check of indoor electronic control P.C. board

Check the both “parts side” and “pattern side” of indoor electronic control P.C. board visually.

Turn OFF the power supply. Remove indoor fan motor connector CN211 and vane motor connector CN151 from the indoor electronic control P.C. board and turn ON the power supply.

Does the unit operate with the remote controller? Does the OPERATION INDICATOR lamp light up by pressing the EMERGENCY OPERATION switch?

Yes

Turn OFF the power supply.

Be sure to check both resistance.

Replace the vane motor.

Is winding resistance of vane motor 0 "?

Replace the fan motor.

Yes

Is winding resistance of fan motor 0 "?

Yes

Turn OFF the power supply.

Replace the fuse.

Is fuse(F11) blown?

Be sure to check both fuse and varistor in any case.

Is varistor(NR11) burnt?

Replace the varistor.

Varistor (NR11)

Fuse (F11)

Indoor electronic control P.C. board

Yes

Replace the indoor electronic control P.C. board.

Yes

Compressor and/ or outdoor fan motor doesn’t operate.

Is there 208/230V AC to between

L1 - L2 on the

outdoor terminal block

Check the outdoor power supply and connection of wiring.

Yes

Compressor does not operate.

Yes

3minutes after the power supply turns ON, is there 208/230V AC between A1-A2 on the compressor contactor?

Operate the unit in COOL or HEAT mode by pressing the EMERGENCY OPERATION switch.

Outdoor fan motor does not operate.

Make the connection of wiring correct.

Check the compressor.

Replace the compressor contactor(52C).

Turn ON the power supply.

Yes

Replace the deicer P.C. board.

Yes

Make the connection of wiring correct.

Yes

Is there 208/230V AC between CN711 2-3 on the deicer P.C. board? w1

Operate the unit in COOL or HEAT mode by pressing the EMERGENCY OPERATION switch.

Make the connection of wiring correct.

Check the outdoor fan motor. Refer to page 34.

Yes

Is there 208/230V AC between CN730 1-3 on the deicer P.C. board? w1

Replace the deicer P.C. board.

Is there 5V DC between J101 - J401 on the deicer P.C. board? w1

Is there 208/230V AC between CN730 1-3 on the deicer P.C. board? w1

Is there 5V DC between J101 - J401 on the deicer P.C. board? w1

w1 Refer to page 42.

Is there 208/230V AC between 2/T1 on the compressor contactor(52C) and

L2 on the outdoor

terminal block?

Is there 208/230V AC between 1/L1 on the compressor contactor(52C) and

L2 on the outdoor

terminal block?

Check of outdoor unit

Compressor and / or outdoor fan motor doesn’t stop.

Check of outdoor unit

1 Turn OFF the power supply. 2 After 30 seconds, turn ON the power supply again. 3 Operate the unit in COOL or HEAT mode by

pressing the EMERGENCY OPERATION switch. 4 Operate the unit for 1 minute or more and stop it by pressing the EMERGENCY OPERATION switch again.

After 30 seconds, does compressor stop?

Yes

After 30 seconds, does outdoor fan motor stop?

Yes

Is there 208/230V AC

between A1-A2 on the compressor contactor?

Yes

Replace the deicer P.C. board.

Is there 208/230V AC

between 2/T1 on the compressor contactor (52C) and

L2 on the outdoor

terminal block?

Replace the compressor contactor (52C).

Yes

Unit operates COOL mode even if it is set to HEAT mode.

Check of R.V. coil

w First, measure the resistance of R.V. coil to confirm it is disconnected or is not short-circuit.

Disconnect the TAB52 on the deicer P.C. board. Turn ON the power supply and operate the indoor unit in HEAT mode by pressing the EMERGENCY OPERATION switch.

After 3 minutes, is there 208/230V AC between CN721 1-3 on the deicer P.C. board?

Yes

Replace the R.V. coil.

Replace the deicer P.C. board.

Make the connection of wiring correct.

Unit operates HEAT mode even if it is set to COOL mode.

Check of R.V. coil

w First, measure the resistance of R.V. coil to confirm it is disconnected or is not short-circuit.

Disconnect the TAB52 on the deicer P.C. board. Turn ON the power supply and operate the indoor unit in COOL mode by pressing the EMERGENCY OPERATION switch.

After 3 minutes, is there 208/230V AC between CN721 1-3 on the deicer P.C. board?

Yes

Replace the deicer P.C. board.

Replace the R.V. coil.

When OPERATION INDICATOR lamp flashes ON and OFF in every 0.5-second. Outdoor unit doesn’t operate.

How to check mis-wiring

Start

Turn OFF the power supply.

Turn ON the power supply.

Rectify the wiring.

Correct the mis-wiring.

Is the power voltage to terminal blocks of indoor/outdoor units normal?

Yes

Turn ON the EMERGENCY OPERATION switch.

(any mode possible)

After 3 minutes that power supply has been turned on, does the compressor start operating?

Yes

Is the terminal blocks11and33on the indoor unit properly connected to their counter parts on outdoor unit?

Yes

Turn OFF the power supply. Check by using checking mode.

Disconnect indoor/outdoor wiring (at indoor terminal blocks 11and 33)

Short circuit between indoor terminal blocks 11and 33.

Turn ON the power supply.

While pressing the OPERATION SELECT button and the TOO COOL button on the remote controller, press the RESET button on the remote controller.

Release the RESET button on the remote controller.

(After 3 seconds, LCD on the remote controller displays all signs.)

Press the OPERATE/STOP(ON/OFF) button on the remote controller to send signal.

Replace the indoor electronic control P.C. board. ❈

Make sure the unit emits a beep tone.

Does the OPERATION INDICATOR lamp on the indoor unit flash on?

Yes

Replace the deicer P.C.board. ❈

Before the unit resumes normal operation.

•Release the checking mode by pressing the RESET button on the remote controller, and then send the unit signal to stop operation.

•Turn OFF the power supply to indoor/outdoor units.

•Get indoor terminal blocks 11and 33opened, and reconnect indoor/ outdoor wiring.

❈ Be sure to turn OFF the power supply to

[]

indoor/outdoor units in replacing P.C. board.

When OPERATION INDICATOR lamp flashes 10-time. Heating/ Cooling doesn't operate.

Measure resistance between CN 661 1 and 2.

Measure resistance between CN 662 3 and 4.

Yes

Replace the thermistor.

Measure resistance between CN 662 1 and 2.

Connect CN661 and CN662. Turn ON the power supply and press the EMERGENCY OPERATION switch.

Does the resistancs of thermistor have the characteristics on page 42?

Yes

Does the unit operate 10 minutes or more?

Replace the deicer P.C.

board.

Ok W1.

W1. It is thought defective contact of the connector.

Turn OFF the power supply.

Discharge temperature thermistor(RT62)

Ambient temperature thermistor(RT63)

Defrost thermistor(RT61)

Check of LEV (Expansion valve)

1 During pressing the OPERATION SELECT button

and the TOO COOL button on the remote controller, press the RESET button.

2 First, release the RESET button.

(After 3 seconds, confirm all displays of the remote controller.)

3 Then release the OPERATION SELECT button.

With remote controller set toward the indoor unit, press the OPERATE/ STOP(ON/ OFF) button and confirm one beep tone.

LEV operates in full-opening direction.

CLOCK

1 During pressing the OPERATION SELECT button and the TOO COOL button on the

remote the controller, press the RESET button.

2 First, release the RESET button.

(After 3 seconds, confirm all displays of the remote controller.) 3 Then release the OPERATION SELECT button.

˚F

AMPM

Do you hear LEV "click, click·······"? Do you touch LEV and feel it vibrate?

Is LEV coil properly fixed to the body?

Yes

Does the resistance of LEV coil have the characterictics?

Replace the LEV coil.

Yes

Properly fix LEV coil to the body.

Replace the deicer P.C. board.

Characteristics of LEV coil

LEV (CN724)

WHT–RED RED–ORN YLW–BRN

BRN–BLU

NOTE : After check of LEV, do the undermentioned operations.

1. Turn OFF the power supply of the unit and turn ON again.

2. Press the RESET button on the remote controller.

Resistance

30.3 " ~ 37.0 "

When OPERATION INDICATOR lamp flashes 6-time. Thermistors in the outdoor unit are abnormal.

Check of outdoor thermistor

w Disconnect the connectors CN661 and/ or CN662 from the deicer P.C. board.

(Check the characteristics of each thermistor.)

TEST POINT DIAGRAM AND VOLTAGE

Indoor coil thermistor(RT12(main), RT13(sub))

Room temperature thermistor (RT11)

32F50 68 86 104122 140

MSH24WN Indoor electronic control P.C. board

Fuse (F11) 250V AC 3.15A

R132

Varistor(NR11)

Fan motor power supply

Power supply input

}

115V AC

5V DC

}

Room temperature thermistor(RT11)

Indoor coil thermistor(RT12(main))

Indoor coil thermistor(RT13(sub))

Receiver P.C. board

Auto restart function Solder the Jumper wire or the Resistor 220Ω to the JR07. (Refer to page 30.)

}

12V DC

Emergency operation switch

Timer short mode point (JPS, JPG) (Refer to page 29.)

MUH24WN

Temperature(-F)

Discharge temperature thermistor(RT62)

Resistance(k")

32 50 68 86 104 122140 158176 194 212230 248

100

200

300

400

500

600

700

800

900

Defrost thermistor (RT61)

Ambient temperature thermistor (RT63)

-4 14 32 50 68 86 104

100

Temperature(-F)

Resistance(k")

Outdoor deicer P.C. board

CN661 1-2 Defrost thermistor (RT61) (Refer to page 40.)

Defrost interval time short pin(JPG1, R871) (Refer to page 29.)

J101

}

J401

(Refer to page 37.)

CN662 1-2 Discharge temperature thermistor (RT62) (Refer to page 40.)

Jumper wire for change in defrost setting (JRF, JRG) (Refer to page 29.)

CN662 3-4 Ambient temperature thermistor (RT63)

(Refer to page 40.)

LEV connector (CN724)

Fan motor connector (CN711)

R.V. coil

}

(CN721)

12V DC

}

Fuse

3.15A / 250V

CN7301-3 208/230V

}

AC (Refer to page 37.)

RELAY OPERATION MSH24WN

COMPRESSOR CONTACTOR

• EACH MODE

MODE THERMOSTAT

COOL & COOL mode of I FEEL CONTROL

DRY & DRY mode of I FEEL CONTROL

HEAT & HEAT mode

OFF

ON ON

52C CONTACTOR

OFF

OFF for 2 min. after unit starts operation.

Repeat of 8 min. ON/3min. OFF operation or 2 min. ON/3 min. OFF operation

Repeat of 4 min. OFF/ 1 min. ON operation

AUTO or set speed

AUTO or set speed links with 52C contactor.

AUTO or set speed

of I FEEL CONTROL

NOTE : Once the compressor is OFF, “3-minute time delay circuit” works at next start-up.

• COIL FROST PREVENTION

MODE

OFF

THERMOSTAT

52C CONTACTOR

OFF

OFF or Very Low speed

COOL & COOL mode of I FEEL CONTROL

DRY & DRY mode of I FEEL

OFF for 5 min. After that, OFF is prolonged until indoor coil thermistor reads termination temperature.

AUTO or set speed

CONTROL

INDOOR FAN SPEED

(1) Slide the sleeve and check if there is a locking lever or not. (2) The terminal with this connector is a terminal

with lock mechanism

1Slide the sleeve. 2Pull the terminal while

pushing the locking lever.

1Hold the sleeve, and pull out the terminal slowly.

In case of terminal with lock mechanism, detach the terminal as shown below. There are two types ( Refer to (1) and (2)) of the terminal with lock mechanism. The terminal with no lock mechanism can be removed by pulling it out. Check the shape of the terminal and work.

<"Terminal with lock mechanism" Detaching points>

Connector

Sleeve

Locking lever

DISASSEMBLY INSTRUCTIONS

11-1. MSH24WN

INDOOR UNIT

OPERATING PROCEDURE

1. Removing the front panel

(1) Remove the screw caps of the front panel.

Remove the screws.

(2) Pull the panel down to your side slightly and unhook the

catches at the top.

2. Removing the electronic control P.C. board, the receiver P.C. board and the display P.C. board NOTE : In case of removing only indoor electronic control

P.C. board work (2) and (3) are not necessary. (1) Remove the front panel. (Refer to 1.) (2) Remove the R.L holder from the bottom of electrical box. (3) Open the R.L holder, remove the receiver P.C. board and

the display P.C. board.

(4) Remove the screw of the electrical cover and the electrical

cover. (5) Pull out indoor electronic control P.C. board slightly. (6) Disconnect all the connectors on the electronic control P.C.

board. (7) Remove the electronic control P.C. board.

Photo 1

Photo 2

R.L holder

Screw of the corner box

PHOTOS

Front panel

Screws

Indoor

electronic control P.C.board

Screw of the electrical cover

Receiver P.C. board

OPERATING PROCEDURE PHOTOS

3. Removing the electrical box

(1) Remove the front panel. (Refer to 1.) (2) Remove the electrical cover. (Refer to 2.) (3) Disconnect the connector of the indoor coil

thermistor (CN112), the fan motor connector (CN211 and CN121) and the vane motor connector (CN151) on the

electronic control P.C. board. (4) Remove the screw of ground wire. (5) Remove the fan motor lead wire, indoor coil thermistor and

ground wire from the electrical box. (6) Remove the lead wire of vane motor from the bottom of

electrical box. (7) Remove the screw of corner box and corner box. (Photo 2) (8) Remove the screw of conduit cover and conduit cover. (9) Remove the screws fixing the conduit plate. (10)

Pull out the conduit plate and the indoor/ outdoor unit con-

necting wire. (11)

Remove the lock nut from the connector of indoor/ outdoor

connecting wire. (12)

Remove the screw fixing the electrical box, remove the

electrical box.

4. Removing the vane motor

(1) Remove the front panel. (Refer to 1.) (2) Remove the electrical cover. (Refer to 2.) (3) Remove the lead wire of vane motor. (Refer to 3.) (4) Remove the R.L. holder. (5) Pull out the drain hose from the nozzle assembly, remove

the nozzle assembly. (6) Remove the screws of the vane motor, disconnect the con-

nector. (7) Remove the vane motor.

Photo 5

Screws of the vane motor

Photo 3

Screws of the conduit plate

Photo 4

Screws of the ground wire

Screw of the conduit cover

Vane motors

Fan motor connectors

Indoor coil thermistor connector

Vane motor connector

Screw of the electrical box

Screws of the vane motor

Vane motor

5. Removing the line flow fan and the indoor fan motor

(1) Remove the front panel. (Refer to 1.) (2) Remove the electrical box. (Refer to 3.) (3) Pull out the drain hose from the nozzle assembly, remove

the nozzle assembly. (4) Remove the water cut. (5) Slide the hole cover, remove the hole cover. (6) Remove the hexagon socket set screw from the line flow

fan. (7) Remove the screws fixing the fan motor, remove the fan

motor. (Be careful not to drop the fan motor because it is

heavy.) (8) Remove the screws fixing the left

side of the heat exchanger.

(9) Lift the left side of the heat exchang-

er. (

) Remove the line flow fan.

Hole cover

Photo 8

Photo 6

Screws fix-

ing the left side of the heat exchanger

Photo 7

Indoor coil thermistor

Water cut

Screws

fixing

the fan

motor

11-2. MUH24WN

OUTDOOR UNIT

OPERATING PROCEDURE

1. Removing the cabinet

(1) Remove the screws of the top panel and the top panel. (2) Remove the screw of the service panel. To remove the

service panel, pull it down toward you and unhook the catches on the both sides.

(3) Remove the screw of the cover panel. To remove the

cover panel.

(4) Remove the screws of the cabinet.

Open the cabinet to a 45-degree angle. Then lift it and unhook the catches to remove.

Photo 2

Discharge pipe

Suction pipe

PHOTOS

Photo 1

Screws of the top panel

Cover panel

Screw of the service panel

Screws of the cabinet

2. Removing the deicer P.C. board

(1) Remove the top panel, the service panel and the cover

panel.

(2) Disconnect all the connectors and the terminals on the

deicer P.C. board.

(3) Remove the deicer P.C. board.

3. Removing the propeller and the outdoor fan motor

(1) Remove the cabinet. (Refer to 1.) (2) Remove the propeller nut and the propeller.

NOTE:Loose the propeller in the rotating direction for

removal. When attaching the propeller, align the mark on the propeller and the motor shaft cut section. Set the propeller in position by using the cut on the shaft and the mark on the propeller.

(3) Remove the lead clamps and disconnect the outdoor

fan motor connector. (Photo 3)

(4) Remove the screws of the outdoor fan motor and the

outdoor fan motor.

Photo 3

Deicer P.C. board

Terminal blocks

Photo 4

Screw of the side panel

Propeller

Propeller nut Screw of the side panel

Screws of the fan motor

Screws of the motor support

Lead clamp

Relay panel

Fan motor connector

Compressor contactor

Screws of the separator support plate

Screws of the valve bed

Screw of the separator

OPERATING PROCEDURE

4. Removing the heat exchanger and compressor

(1) Remove the screws of the rear panel. Remove the screws

of the valve bed and the valve bed. (The valve bed is fixed by the catches on the right and left sides. Lift it to remove.) Open the rear panel to the rear to remove.

NOTE :

All panels are fixed by catches, and must be removed by up and down.

(2) Remove the screws of the side panel and the side panel.

(Photo 4) (3) Remove the screws of the rear guard and the rear guard. (4) Remove the screws of the separator support plate and

the separator support plate. (Photo 4) (5) Remove the screws of the motor support and the motor

support. (Photo 4) (6) Remove the relay panel. (Photo 3) (7) Remove the fan motor lead wire from lead clamp.

(Photo 4) (8) Remove the soundproof felt. (9) Remove the screws of the separator and the separator. (10)

Recover gas from the refrigerant circuit. (11)

Remove the heat exchanger.

Detach the welded part of pipe. (12)

Remove the nuts of the compressor and the compressor.

Detach the welded part of the suction pipe and the dis-

charge pipe. (Photo 2)

Photo 5

Screws of the rear panel

Photo 6

PHOTOS

Screws of the rear guard

Heat exchanger

Accumulator

Photo 7

Compressor

Soundproof felt

Screw of the separator

Stop valve

MSH24WN

E02 527 970 E02 527 234 E02 527 000 E02 408 142 E02 527 067 E02 527 010 E02 527 100 E02 527 975 E02 530 007

INSTALLATION PLATE BOX (W

)

FRONT PANEL ASSEMBLY(W) CATCH SCREW CAP (W

)

GRILLE (W

)

AIR FILTER CORNER BOX RIGHT LAMP PANEL

Symbol

in Wiring

Diagram

Q'ty/unit

Including No.4,5,6

4PCS/ SET 3PCS/ SET

Remarks

Part No.

NO.

Part Name

1 2 3 4 5 6 7 8 9

1 1 1 4 3 1 2 1 1

(W)

E02 527 620 E02 527 666 E02 527 667

INDOOR HEAT EXCHANGER UNION (GAS

)

UNION (LIQUID

)

{

5/8

{

3/8

10 11 12

1 1 1

PARTS LIST

MSH24WN (W) 12-1. INDOOR UNIT STRUCTURAL PARTS

1 2

12-2. INDOOR UNIT HEAT EXCHANGER

CATCH

SCREW CAP

12-1. INDOOR UNIT STRUCTURAL PARTS

Part number that is circled is not shown in the illustration.

Optional parts (See back cover.)

12-2. INDOOR UNIT HEAT EXCHANGER

MSH24WN

E02 527 302 E02 408 509 E02 001 504 E02 408 702 E02 527 235 E02 527 040 E02 527 041 E02 784 382 E02 784 385 E02 527 034 E02 784 300 E02 448 303 E02 408 303 E02 527 333 E02 528 329 E02 527 468 E02 785 452 E02 527 308 E02 545 375 E02 527 307 E02 528 034 E02 529 034

1 2 3 4 5 6 7 8 9

11 12 13 14 15 16 17 18 19 20 21 22

LINE FLOW FAN BEARING MOUNT SLEEVE BEARING DRAIN HOSE NOZZLE ASSEMBL Y VANE UPPER (W

)

VANE LOWER (W

)

FUSE VARISTOR VANE CRANK SET INDOOR FAN MOTOR ASSEMBLY VANE MOTOR (VERTICAL

)

VANE MOTOR (HORIZONTAL

)

MOTOR BAND DISPLAY P.C. BOARD RECEIVER P.C. BOARD ELECTRONIC CONTROL P.C. BOARD ROOM TEMPERATURE THERMISTOR TERMINAL BLOCK INDOOR COIL THERMISTOR VANE MOTOR SUPPORT SET (RIGHT

)

VANE MOTOR SUPPORT SET (LEFT

)

Symbol

in Wiring

Diagram

Q'ty/unit

3.15A

RIGHT & LEFT UP & DOWN

Remarks

Part No.

NO.

Part Name

F11

NR11

MF MV2 MV1

RT11

RT12, RT13

1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 1 1 1

(W)

RC4W33 Including RUBBER MOUNT

AUTO RESTART Including No.16

MSH24WN (W)

23 24

E02 785 426 E02 527 083

REMOTE CONTROLLER REMOTE CONTROLLER HOLDER

1 1

12-3. INDOOR UNIT FUNCTIONAL PARTS AND

ELECTRICAL PARTS

12-4. ACCESSORY AND

REMOTE CONTROLLER

2 3

SLEEVE BEARING

ROOM

TEMPERATURE THERMISTOR

5 6

FUSE

VARISTOR

179

12-3. INDOOR UNIT FUNCTIONAL PARTS AND ELECTRICAL PARTS

Part numbers that are circled are not shown in the illustration.

12-4. ACCESSORY AND REMOTE CONTROLLER

MUH24WN 12-5. OUTDOOR UNIT STRUCTURAL PARTS, ELECTRICAL PARTS

AND FUNCTIONAL PARTS

2322

MUH24WN

Symbol

in Wiring

Diagram

Q'ty/unit

Remarks

Part No.

NO.

Part Name

E02 813 297 E02 528 309 E02 529 630 E02 784 301 E02 214 501 E07 070 508 E02 813 290 E02 813 232 E02 819 009 E02 784 521 E02 527 506 E02 784 900 E02 527 662 E02 527 661 E02 529 310 E02 474 642 E07 001 641 E02 785 490 E02 444 961 E02 527 640 E02 528 493 E02 813 245 E02 813 006 E02 480 374 E02 481 374 E02 784 351 E02 784 340 E02 544 353 E02 128 383 E02 785 451 E02 813 522 E02 813 523 E02 814 249 E02 527 515 E02 784 382 E02 096 642 E02 785 936 E02 529 936

1 2 3 4 5 6 7 8 9

11 12 13 14 15 16 17 18 19 20 21 22 23

24 25

26 27 28 29 30 31 32 33 34 35

TOP PANEL THERMISTOR OUTDOOR HEAT EXCHANGER OUTDOOR FAN MOTOR PROPELLER PROPELLER NUT BASE CABINET HANDLE FAN GUARD COMPRESSOR RUBBER SET COMPRESSOR STOP VALVE (LIQUID

)

STOP VALVE (GAS

) DEFROST THERMISTOR FUSIBLE PLUG

SERVICE PORT R.V. COIL 4-WAY VALVE EXPANSION VALVE EXPANSION VALVE COIL SERVICE PANEL COVER PANEL TERMINAL BLOCK TERMINAL BLOCK OUTDOOR FAN CAPACITOR COMPRESSOR CONTACTOR COMPRESSOR CAPACITOR SURGE ABSORBER DEICER P.C. BOARD REAR PANEL REAR GUARD SIDE PANEL MOTOR SUPPORT FUSE CHECK VALVE CAPILLARY TUBE (TAPER PIPE) CAPILLARY TUBE (TAPER PIPE)

NEW WHITE(Brighter)

DISCHARGE, AMBIENT

RA6N66-

NEW WHITE(Brighter) NEW WHITE(Brighter) NEW WHITE(Brighter) NEW WHITE(Brighter) 4RUBBERS/SET PH33NPBT

{

3/8

{

5/8

NEW WHITE(Brighter) NEW WHITE(Brighter) 4P FIGURE A 4P FIGURE B

5.0+/440V AC

35+/370V AC

NEW WHITE(Brighter) NEW WHITE(Brighter) NEW WHITE(Brighter)

250V/3.15A

{0.17✕{0.12✕11-13/16 {0.17✕{0.12✕1-31/32

RT62, RT63

RT61

21S4

LEV

TB1 TB2

52C

DSAR

F61

1 1 1 1 1 1 1 1 3 1 4 1 1 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

12-5. OUTDOOR UNIT STRUCTURAL PARTS, ELECTRICAL PARTS

AND FUNCTIONAL PARTS

Part numbers that are circled are not shown in the illustration.

Pipe length

Cross-

section

Part No.Model

A-Gas(in.)

B-Liquid(in.)

Pipe size

Insulation

(in.)

Additional refrigerant

charge

R22(oz.)

Outside

diameter

Wall

thickness

Outside

diameter

Wall

thickness

MSH24WN MUH24WN

10ft. 16ft. 23ft. 33ft. 49ft.

4.29

12.86

5/8 0.0315 3/8

C 1-7/32 D 1-1/16

0.0285

MAC-860PI MAC-861PI MAC-862PI MAC-863PI MAC-864PI

OPTIONAL PARTS

13-1. REFRIGERANT PIPES

The air conditioner has flared connections its on indoor and outdoor sides. Please use the optional extension pipe as follows.

13-2. AIR CLEANING FILTER

● AIR CLEANING FILTER removes fine dust of 0.01 micron from air by means of static electricity.

● Normal life of AIR CLEANING FILTER is 4 months. However, when it becomes dirty, replace it as soon as possible.

● Clogged AIR CLEANING FILTER may reduce the air conditioner capacity or cause frost on the air outlet.

● DO NOT reuse AIR CLEANING FILTER even if it is washed.

● DO NOT remove or attach AIR CLEANING FILTER during unit operation.

Model

MSH24WN

Part No.

MAC-1700FT

13-3. DEODORIZING FILTER

● DEODORIZING FILTER removes ammonia and hydrogen sulphide emitted from tobacco, and odor of pets.

● Clean DEODORIZING FILTER every two weeks. If the filter is particularly dirty, clean the filter more often.

● For cleaning, soak the filter in warm water for a while, and then wash and rinse it. Dry the filter in the shade

thoroughly.

● When the filter color is still dark even after cleaning, replace the filter with a new one. Replace the filter at least once a year.

Model

MSH24WN

● DEODORIZING FILTER and AIR CLEANING FILTER can be attached on either side.

Part No.

MAC-2200DF

Air cleanig filter (White bellows type)

Deodorizing filter (Gray sponge type)

New publication, effective Jan. 2004 Specifications subject to change without notice.

3400 Lawrenceville Suwanee Road ● Suwanee, Georgia 30024

Toll Free: 800-433-4822 ● Toll Free Fax: 800-889-9904

Specifications are subject to change without notice.

www.mrslim.com

Mitsubishi Electric MSH24WN, MUH24WN, MSH24WNW Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual