Midea MEHS-12PSH1, MEHSU-12PHH2, MEHSU-09PHH2, MEHSU-24PHH2, MEHS-30PSH2 Service Manual

...

Mission 3D Inverter Series

Service Manual 2016

MBSUL-A-1604

CONTENTS

1. Precaution .................................................................................................................................................... 3

1.1 Safety Precaution .......................................................................................................................... 3

1.2 Warning ......................................................................................................................................... 3

2. Model list ...................................................................................................................................................... 6

3. Dimension .................................................................................................................................................... 7

3.1 Indoor Unit ..................................................................................................................................... 7

3.2 Outdoor Unit .................................................................................................................................. 9

4. Refrigerant Cycle Diagram ....................................................................................................................... 10

5. Wiring Diagram ........................................................................................................................................... 11

5.1 Indoor Unit .................................................................................................................................... 11

5.2 Outdoor Unit ................................................................................................................................ 13

6 Installation Details ...................................................................................................................................... 15

6.1 Wrench torque sheet for installation ........................................................................................... 15

6.2 Connecting the cables ................................................................................................................ 15

6.3 Pipe length and the elevation ..................................................................................................... 15

6.4 Installation for the first time ......................................................................................................... 16

6.5 Adding the refrigerant after running the system for many years ................................................ 16

6.6 Re-installation while the indoor unit need to be repaired ........................................................... 17

6.7 Re-installation while the outdoor unit need to be repaired ......................................................... 18

7. Operation Characteristics ......................................................................................................................... 19

8. Electronic function .................................................................................................................................... 20

8.1 Abbreviation ................................................................................................................................ 20

8.2 Display function ........................................................................................................................... 20

8.3 Main Protection ........................................................................................................................... 21

8.4 Operation Modes and Functions ................................................................................................. 22

9. Troubleshooting ......................................................................................................................................... 28

9.1 Indoor Unit Error Display ............................................................................................................. 29

9.2 Outdoor unit error display ........................................................................................................... 30

9.3 Diagnosis and Solution ............................................................................................................... 34

10 Disassembly Instructions ........................................................................................................................ 63

10.1 Indoor unit ................................................................................................................................. 63

10.2 Outdoor unit .............................................................................................................................. 67

1. Precaution

1.1 Safety Precaution

 To prevent injury to the user or other

people and property damage, the following

instructions must be followed.

 Incorrect operation due to ignoring

instruction will cause harm or damage.

 Before service the unit, be sure to

read this service manual at first.

1.2 Warning

 Installation

 Do not use a defective or underrated

circuit breaker. Use this appliance on a

dedicated circuit.

There is risk of fire or electric shock.

 For electrical work, contact the dealer,

seller, a qualified electrician, or an

authorized service center.

Do not disassemble or repair the product,

there is risk of fire or electric shock.

 Always ground the product.

There is risk of fire or electric shock.

 Install the panel and the cover of

control box securely.

There is risk of fire of electric shock.

 Always install a dedicated circuit and

breaker.

Improper wiring or installation may cause fore

or electric shock.

 Use the correctly rated breaker of

fuse.

There is risk of fire or electric shock.

 Do not modify or extend the power

cable.

There is risk of fire or electric shock.

 Do not install, remove, or reinstall the

unit by yourself (customer).

There is risk of fire, electric shock, explosion,

or injury.

 Be caution when unpacking and

installing the product.

Sharp edges could cause injury, be especially

careful of the case edges and the fins on the

condenser and evaporator.

 For installation, always contact the

dealer or an authorized service center.

 Do not install the product on a

defective installation stand.

 Be sure the installation area does not

deteriorate with age.

If the base collapses, the air conditioner could

fall with it, causing property damage, product

failure, and personal injury.

 Do not let the air conditioner run for a

long time when the humidity is very high

and a door or a window is left open.

 Take care to ensure that power cable

could not be pulled out or damaged during

operation.

There is risk of fire or electric shock.

 Do not place anything on the power

cable.

There is risk of fire or electric shock.

 Do not plug or unplug the power

supply plug during operation.

There is risk of fire or electric shock.

 Do not touch (operation) the product

with wet hands.

 Do not place a heater or other

appliance near the power cable.

There is risk of fire and electric shock.

 Do not allow water to run into

electrical parts.

It may cause fire, failure of the product, or

electric shock.

 Do not store or use flammable gas or

combustible near the product.

There is risk of fire or failure of product.

 Do not use the product in a tightly

closed space for a long time.

Oxygen deficiency could occur.

 When flammable gas leaks, turn off

the gas and open a window for ventilation

before turn the product on.

 If strange sounds or smoke comes

from product, turn the breaker off or

disconnect the power supply cable.

There is risk of electric shock or fire.

 Stop operation and close the window

in storm or hurricane. If possible, remove

the product from the window before the

hurricane arrives.

There is risk of property damage, failure of

product, or electric shock.

 Do not open the inlet grill of the

product during operation. (Do not touch the

electrostatic filter, if the unit is so equipped.)

There is risk of physical injury, electric shock,

or product failure.

 When the product is soaked, contact

an authorized service center.

There is risk of fire or electric shock.

 Be caution that water could not enter

the product.

There is risk of fire, electric shock, or product

damage.

 Ventilate the product from time to

time when operating it together with a stove

etc.

There is risk of fire or electric shock.

 Turn the main power off when

cleaning or maintaining the product.

There is risk of electric shock.

 When the product is not be used for a

long time, disconnect the power supply plug

or turn off the breaker.

There is risk of product damage or failure, or

unintended operation.

 Take care to ensure that nobody

could step on or fall onto the outdoor unit.

This could result in personal injury and

product damage.

 CAUTION

 Always check for gas (refrigerant)

leakage after installation or repair of

product.

Low refrigerant levels may cause failure of

product.

 Install the drain hose to ensure that

water is drained away properly.

A bad connection may cause water leakage.

 Keep level even when installing the

product.

It can avoid vibration of water leakage.

 Do not install the product where the

noise or hot air from the outdoor unit could

damage the neighborhoods.

It may cause a problem for your neighbors.

 Use two or more people to lift and

transport the product.

 Do not install the product where it will

be exposed to sea wind (salt spray) directly.

It may cause corrosion on the product.

Corrosion, particularly on the condenser and

evaporator fins, could cause product

malfunction or inefficient operation.

 Operational

 Do not expose the skin directly to

cool air for long time. (Do not sit in the

draft).

 Do not use the product for special

purposes, such as preserving foods, works

of art etc. It is a consumer air conditioner,

not a precision refrigerant system.

There is risk of damage or loss of property.

 Do not block the inlet or outlet of air

flow.

 Use a soft cloth to clean. Do not use

harsh detergents, solvents, etc.

There is risk of fire, electric shock, or damage

to the plastic parts of the product.

 Do not touch the metal parts of the

product when removing the air filter. They

are very sharp.

 Do not step on or put anything on the

product. (outdoor units)

 Always insert the filter securely.

Clean the filter every two weeks or more

often if necessary.

A dirty filter reduces the efficiency of the air

conditioner and could cause product

malfunction or damage.

 Do not insert hands or other objects

through air inlet or outlet while the product

is operated.

 Do not drink the water drained from

the product.

 Use a firm stool or ladder when

cleaning or maintaining the product.

Be careful and avoid personal injury.

 Replace the all batteries in the remote

control with new ones of the same type. Do

not mix old and new batteries or different

types of batteries.

There is risk of fire or explosion.

 Do not recharge or disassemble the

batteries. Do not dispose of batteries in a

fire.

They may burn of explode.

 If the liquid from the batteries gets

onto your skin or clothes, wash it well with

clean water. Do not use the remote of the

batteries have leaked.

2. Model list

Model Names of Indoor/Outdoor Units

3D inverter

Capacity Indoor units Outdoor units

9k(115V) MEHS-09PSH1 MCHS-09PSH1

9k MEHSU-09PHH2 MCHSU-09PHH2

12k(115V)

MEHS-12PSH1

MCHS-12PSH1

12k MEHSU-12PHH2 MCHSU-12PHH2

18k

MEHSU-18PHH2 MCHSU-18PHH2

24k MEHSU-24PHH2 MCHSU-24PHH2

30k MEHS-30PSH2 MCHS-30PSH2

36k MEHS-36PSH2 MCHS-36PSH2

3. Dimension

3.1 Indoor Unit

Model W D H

9k(115V&230V) 31.89(810) 7.87(200) 11.81(300)

12k(115V&230V) 31.89(810) 7.87(200) 11.81(300)

18k 42.91(1090) 9.25(235) 13.31(338)

24k 42.91(1090) 9.25(235) 13.31(338)

30k 54.15(1350) 10.71(272) 14.37(365)

36k 54.15(1350) 10.71(272) 14.37(365)

For 9k & 12k:

For 18k & 24k:

For 30k & 36k:

3.2 Outdoor Unit

More than 60cm(23.6in)

More than 70cm(27.6in)

More than 30cm(11.8in)

More than 60cm(23.6in) (Service space)

More than 30cm(11.8in)

Note: The above drawing is only for reference. The appearance of your units may be different.

Model W in(mm) D in(mm) H in(mm) W1 in(mm) A in(mm) B in(mm)

9k(115V) 30.31(770) 11.81(300) 21.85(555) 33.07 (840) 19.2(487) 11.73(298)

12k(115V) 31.50(800) 13.11(333) 21.81(554) 34.25(870) 20.24(514) 13.39(340)

9k(230V) 31.50(800) 13.11(333) 21.81(554) 34.25(870) 20.24(514) 13.39(340)

12k(230V) 31.50(800) 13.11(333) 21.81(554) 34.25(870) 20.24(514) 13.39(340)

18k 35.98(845) 14.29(363) 27.63(702) 35.98(914) 21.26(540) 13.78(350)

24k

37.24(946) 16.54(420) 31.89(810) 40.55(1030) 26.50(673) 15.87(403)

30k

36k

4. Refrigerant Cycle Diagram

LIQUID SIDE

GAS SIDE

HEAT EXCHANGE (EVAPORATOR)

HEAT EXCHANGE (CONDENSER)

COMPRESSOR

2-WAY VALVE

3-WAY VALVE

4-WAY VALVE

COOLING

HEATING

T2 Evaporator temp. sensor

T1 Room temp. sensor

ACCUMULATOR

INDOOR OUTDOOR

CHECK VALVE (Heating Model only)

CAPILIARY TUBE

5. Wiring Diagram

5.1 Indoor Unit

MEHS-09PSH1, MEHS-12PSH1,

MEHSU-09PHH2, MEHSU-12PHH2

MEHSU-18PHH2, MEHSU-24PHH2, MEHS-30PSH2, MEHS-36PSH2,

5.2 Outdoor Unit

MCHS-09PSH1, MCHS-12PSH1,

MCHSU-09PHH2, MCHSU-12PHH2, MCHSU-18PHH2,

MCHSU-24PHH2,, MCHS-30PSH2, MCHS-36PSH2,

6 Installation Details

6.1 Wrench torque sheet for installation

Outside diameter

Torque

Additional tightening

torque

6.35mm

1/4in

1500N.cm(153kgf.cm/

11lb.ft)

1600N.cm(163kgf.cm/1

1.8lb.ft)

9.52mm

3/8in

2500N.cm(255kgf.cm/

18.4lb.ft)

2600N.cm(265kgf.cm/1

9.18lb.ft)

12.7mm

1/2in

3500N.cm(357kgf.cm/

25.8lb.ft)

3600N.cm(367kgf.cm/2

6.55lb.ft)

15.9mm

5/8in

4500N.cm(459kgf.cm/

33.19lb.ft)

4700N.cm(479kgf.cm/3

4.67lb.ft)

Ф19mm

3/4in

6500N.cm(663kgf.cm/

47.94lb.ft)

6700N.cm(683kgf.cm/4

9.41lb.ft)

6.2 Connecting the cables

The power cord should be selected according

to the following specifications sheet.

Appliance Amps AWG Wire Size

10 18

13 16

18 14

25 12

30 10

The cable size and the current of the fuse or

switch are determined by the maximum

current indicated on the nameplate which

located on the side panel of the unit. Please

refer to the nameplate before selecting the

cable, fuse and switch.

6.3 Pipe length and the elevation

Models

Pipe size

Gas Liquid

9k 3/8in(Ф9.52mm) 1/4in(Ф6.35mm)

12k

1/2in(Ф12.7mm) 1/4in(Ф6.35mm)

18k

24k

5/8in (Ф15.9mm) 3/8in(Ф9.52mm)

30k

36k

Models

Standard

length

Max. Elevation

Max. Length

Additional

refrigerant

&12k

7.5m(24.6ft) 10m(32.8ft) 25m(82.0ft) 15g/m(0.16oz/ft)

18k

7.5m(24.6ft)

20m(65ft) 30m(98ft) 15g/m(0.16oz/ft)

24k

7.5m(24.6ft)

25m(82ft) 50m(164ft) 30g/m(0.32oz/ft)

30k

7.5m(24.6ft)

25m(82ft) 50m(164ft) 30g/m(0.32oz/ft)

36k

7.5m(24.6ft)

30m(82.0ft) 65m(213ft)

30g/m(0.32oz/ft)

6.4 Installation for the first time

Air and moisture in the refrigerant system have

undesirable effects as below:

● Pressure in the system rises.

● Operating current rises.

● Cooling or heating efficiency drops.

● Moisture in the refrigerant circuit may

freeze and block capillary tubing.

● Water may lead to corrosion of parts in the

refrigerant system.

Therefore, the indoor units and the pipes

between indoor and outdoor units must be leak

tested and evacuated to remove gas and

moisture from the system.

Gas leak check (Soap water method):

Apply soap water or a liquid neutral

detergent on the indoor unit connections or

outdoor unit connections by a soft brush to

check for leakage of the connecting points of

the piping. If bubbles come out, the pipes have

leakage.

1. Air purging with vacuum pump

1) Completely tighten the flare nuts of the

indoor and outdoor units, confirm that both

the 2-way and 3-way valves are set to the

closed position.

2) Connect the charge hose with the push pin

of handle lo to the 3-way valves gas service

port..

3) Connect the charge hose of handle hi

connection to the vacuum pump.

4) Fully open the handle Lo of the manifold

valve.

5) Operate the vacuum pump to evacuate.

6) Make evacuation for 30 minutes and check

whether the compound meter indicates

-0.1Mpa(14.5Psi). If the meter does not

indicate -0.1Mpa(14.5Psi) after pumping 30

minutes, it should be pumped 20 minutes

more. If the pressure can’t achieve

-0.1Mpa(14.5Psi) after pumping 50 minutes,

please check if there are some leakage points.

Fully close the handle Lo valve of the

manifold valve and stop the operation of the

vacuum pump. Confirm that the gauge needle

does not move (approximately 5 minutes after

turning off the vacuum pump).

7) Turn the flare nut of the 3-way valves about

45° counterclockwise for 6 or 7seconds

after the gas coming out, then tighten the

flare nut again. Make sure the pressure

display in the pressure indicator is a little

higher than the atmosphere pressure. Then

remove the charge hose from the 3 way

valve.

8) Fully open the 2 way valve and 3 way valve

and securely tighten the cap of the 3 way

valve.

6.5 Adding the refrigerant after running the system for many years

Procedure:

1). Connect the charge hose to the 3-way service

port, open the 2-way valve and the 3-way valve.

Connect the charge hose to the valve at the

bottom of the cylinder. If the refrigerant is

R410A, make the cylinder bottom up to ensure

liquid charge.

2). Purge the air from the charge hose.

Open the valve at the bottom of the cylinder

and press the check valve on the charge set to

purge the air (be careful of the liquid

refrigerant).

3) Put the charging cylinder onto the electronic

scale and record the weight.

4) Operate the air conditioner at the cooling

mode.

5) Open the valves (Low side) on the charge set

and charge the system with liquid refrigerant.

6).When the electronic scale displays the proper

weight (refer to the gauge and the pressure of the

low side), disconnect the charge hose from the

3-way valve’s service port immediately and turn

off the air conditioner before disconnecting the

hose.

7). Mount the valve stem caps and the service

port

Use torque wrench to tighten the service port

cap to a torque of 18N.m.

Be sure to check for gas leakage.

6.6 Re-installation while the indoor unit need to be repaired

1. Collecting the refrigerant into the outdoor

unit

Procedure

1). Confirm that both the 2-way and 3-way valves

are set to the opened position

Remove the valve stem caps and confirm that the

valve stems are in the opened position.

Be sure to use a hexagonal wrench to operate the

valve stems.

2). Connect the charge hose with the push pin of

handle lo to the 3-way valves gas service port.

3). Air purging of the charge hose.

Open the handle Lo valve of the manifold valve

slightly to purge air from the charge hose for 5

seconds and then close it quickly.

4). Set the 2-way valve to the close position.

5). Operate the air conditioner at the cooling cycle

and stop it when the gauge indicates

0.1Mpa(14.5Psi).

6). Set the 3-way valve to the closed position

immediately

Do this quickly so that the gauge ends up

indicating 0.3Mpa(43.5Psi) to 0.5 Mpa(72.5Psi).

Disconnect the charge set, and tighten the 2-way

and 3-way valve’s stem nuts.

Use a torque wrench to tighten the 3-way valves

service port cap to a torque of 18N.m.

Be sure to check for gas leakage.

2.Air purging with vacuum pump

1) Completely tighten the flare nuts of the indoor

and outdoor units, confirm that both the 2-way

and 3-way valves are set to the closed position.

2) Connect the charge hose with the push pin of

handle lo to the 3-way valves gas service port.

3) Connect the charge hose of handle hi

connection to the vacuum pump.

4) Fully open the handle Lo of the manifold valve.

5) Operate the vacuum pump to evacuate.

6) Make evacuation for 30 minutes and check

whether the compound meter indicates

-0.1Mpa(14.5Psi). If the meter does not indicate

-0.1Mpa(14.5Psi) after pumping 30 minutes, it

should be pumped 20 minutes more. If the

pressure can’t achieve -0.1Mpa(14.5Psi) after

pumping 50 minutes, please check if there are

some leakage points. Fully close the handle Lo

valve of the manifold valve and stop the operation

of the vacuum pump. Confirm that the gauge

needle does not move (approximately 5 minutes

after turning off the vacuum pump).

7)Turn the flare nut of the 3-way valves about 45°

counterclockwise for 6 or 7seconds after the gas

coming out, then tighten the flare nut again. Make

sure the pressure display in the pressure

indicator is a little higher than the atmosphere

pressure. Then remove the charge hose from the

3 way valve.

8) Fully open the 2 way valve and 3 way valve

and securely tighten the cap of the 3 way valve.

6.7 Re-installation while the outdoor unit need to be repaired

1. Evacuation for the whole system

Procedure:

1). Confirm that both the 2-way and 3-way

valves are set to the opened position.

2). Connect the vacuum pump to 3-way valve’s

service port.

3). Evacuation for approximately one hour.

Confirm that the compound meter indicates

-0.1Mpa(14.5Psi).

4). Close the valve (Low side) on the charge set,

turn off the vacuum pump, and confirm that the

gauge needle does not move (approximately 5

minutes after turning off the vacuum pump).

5). Disconnect the charge hose from the vacuum

pump.

2. Refrigerant charging

Procedure:

1). Connect the charge hose to the charging

cylinder, open the 2-way valve and the 3-way

valve

Connect the charge hose which you

disconnected from the vacuum pump to the

valve at the bottom of the cylinder. If the

refrigerant is R410A, make the cylinder bottom

up to ensure liquid charge.

2). Purge the air from the charge hose

Open the valve at the bottom of the cylinder

and press the check valve on the charge set to

purge the air (be careful of the liquid

refrigerant).

3) Put the charging cylinder onto the electronic

scale and record the weight.

4). Open the valves (Low side) on the charge set

and charge the system with liquid refrigerant

If the system cannot be charge with the specified

amount of refrigerant, or can be charged with a

little at a time (approximately 150g each time) ,

operating the air conditioner in the cooling cycle;

however, one time is not sufficient, wait

approximately 1 minute and then repeat the

procedure.

5).When the electronic scale displays the proper

weight, disconnect the charge hose from the

3-way valve’s service port immediately

If the system has been charged with liquid

refrigerant while operating the air conditioner,

turn off the air conditioner before disconnecting

the hose.

6). Mounted the valve stem caps and the service

port.

Use torque wrench to tighten the service port

cap to a torque of 18N.m.

Be sure to check for gas leakage.

7. Operation Characteristics

CAUTION:

1. If the air conditioner is used beyond the above conditions, certain safety protection features

may come into operation and cause the unit to operate abnormally.

2. The room relative humidity should be less than 80%. If the air conditioner operates beyond this

figure, the surface of the air conditioner may attract condensation. Please set the vertical air flow

louver to its maximum angle (vertically to the floor), and set HIGH fan mode.

3. The optimum performance will be achieved during this operating temperature zone.

9k(115V) 12k(115V) 9k(230V) 12k(230V) 18k 24k 30k 36k

Operating Range

Cooling

Outdoor

Min - Max

°F (°C)

4-122

(-20-50)

4-122

(-20-50)

4-122

(-20-50)

4-122

(-20-50)

4-122

(-20-50)

4-122

(-20-50)

4-122

(-20-50)

4-122

(-20-50)

Indoor Min

- Max DB

°F (°C)

63-86

(17-30)

63-86

(17-30)

63-86

(17-30)

63-86

(17-30)

63-86

(17-30)

63-86

(17-30)

63-86

(17-30)

63-86

(17-30)

Indoor Min

- Max WB

°F (°C)

59-84

(15-29)

59-84

(15-29)

59-84

(15-29)

59-84

(15-29)

59-84

(15-29)

59-84

(15-29)

59-84

(15-29)

59-84

(15-29)

Heating

Outdoor

DB Min –

Max

°F

(°C)

4-86

(-20-30)

4-86

(-20-30)

(-22)-86

(-30-30)

(-22)-86

(-30-30)

(-22)-86

(-30-30)

(-22)-86

(-30-30)

4-86

(-20-30)

4-86

(-20-30)

Outdoor

WB Min –

Max

°F (-4)-77 (-4)-77 (-4)-77 (-4)-77 (-4)-77 (-4)-77 (-4)-77 (-4)-77

(°C) (-20-25) (-20-25) (-20-25) (-20-25) (-20-25) (-20-25) (-20-25) (-20-25)

Indoor DB

Min –Max

°F

(°C)

32-86

(0-30)

32-86

(0-30)

32-86

(0-30)

32-86

(0-30)

32-86

(0-30)

32-86

(0-30)

32-86

(0-30)

32-86

(0-30)

8. Electronic function

8.1 Abbreviation

T1: Indoor room temperature

T2: Coil temperature of evaporator

T3: Coil temperature of condenser

T4: Outdoor ambient temperature

TP: Compressor discharge temperature

8.2 Display function

8.2.1 Icon explanation on indoor display board.

Digital display:

Displays the temperature settings when the air

conditioner is operational.

Displays the room temperature in FAN mode.

Displays the self-diagnostic codes.

Dispalys ‘ ’ for three seconds when Timer

ON, Fresh, Swing, Turbo or Silence feature is

activated.

Dispalys ‘ ’ for three seconds when Timer

OFF is set.

Dispalys ‘ ’ for three seconds when Fresh,

Swing, Turbo or Silence feature is cancelled.

Dispalys ‘ ’ under deforsting operation.

Dispalys ‘ ’ when anti-cold air feature is

activated under heating mode.

Dispalys ‘ ’ during self clean operation (if

aplicable).

Dispalys ‘ ’ under 8℃ heating operation (if

aplicable).

When ECO function(optional) is actived,the

“ ” illuminates gradually one by one as

In one second interval.

WIFI control display(optional)

Displays when the WIFI control feature is

actived. (Not available when the unit does not

have this function)

NOTE:

A guide on using the infrared remotr is included

in this literature package.

8.3 Main Protection

8.3.1 Three minutes delay at restart for

compressor

Less than 1 minute delay for the 1st time

stand-up and 3 minutes delay for others.

8.3.2 Temperature protection of compressor

top

The unit will stop working when the compressor

top temp. protector cut off, and will restart after

the compressor top temp. protector restart.

8.3.3 Temperature protection of compressor

discharge

Compressor discharge temp. TP>115℃ for 5s,

compressor stops.

8.3.4 Fan speed is out of control

When indoor fan speed keeps too low

(300RPM) for certain time, the unit will stop and

the LED will display the failure

8.3.5 Inverter module protection

The Inverter module has a protection function

about current, voltage and temperature. If these

protections happen, the corresponding code

will display on indoor unit and the unit will stop

working.

8.3.6 Indoor fan delayed open function

When the unit starts up, the louver will be active

immediately and the indoor fan will open 7s

later.

If the unit runs in heating mode, the indoor fan

will be also controlled by anti-cold wind

function.

8.3.7 Compressor preheating functions

Preheating permitting condition: When T4(outdoor ambient temperature)＜3°C,

the preheating function will be activated.

8.3.8 Sensor protection at open circuit and

breaking disconnection.

When there’s only one temperature sensor in

malfunction , the air conditioner will keep

working but show the error code, in case of any

emergency use.

When there’s more than one temperature

sensor in malfunction, the air conditioner will

stop working

8.3.9 Refrigerant leakage detection

This function is only active in cooling mode. It

can better prevent the compressor being

damaged by refrigerant leakage or compressor

overload.

Open condition:

When compressor is active, the value of the

Coil temperature of evaporator T2 has no

change or very little change.

8.4 Operation Modes and Functions

8.4.1 Fan mode

(

1) Outdoor fan and compressor stop. (2) Temperature setting function is disabled, and no setting temperature is displayed. (3) Indoor fan can be set to high/med/low/auto. (4) The louver operates same as in cooling mode. (5) Auto fan:

T 1

8.4.2 Cooling Mode

8.4.2.1 Compressor running rules

When T1-Ts<-2℃, the compressor will stop, when T1—TS>-0.5℃，the compressor will be

activated.

When the AC run in mute mode, the

compressor will run with low frequency.

When the current is more than setting value,

the current protection function will be activated,

and the compressor will stop.

8.4.2.2 Outdoor fan running rules

The outdoor unit will be run at different fan

speed according to T4.

For different outdoor units, the fan speeds are

different

T 4

A +

8.4.2.3Indoor fan running rules

In cooling mode, indoor fan runs all the time

and the speed can be selected as high,

medium, low and auto.

When the setting temp. is reached, if the

compressor stop running, indoor fan motor will

run in Minimum speed or setting speed.

The indoor fan is controlled as below:

Setting fan

speed

Actual fan speed

H+(H+=H+G) A H（=H） B C

M+(M+=M+Z) D M(M=M) E F

L+(L+=L+D) G L(L=L) H I

T1-Td ℃(°F)

L-(L-=L-D)

H-（H-=H-G)

M-(M-=M-Z)

The auto fan acts as below rules:

T 1

8.4.2.4 Condenser temperature protection

Resume

Off

Decrease

Hold

When condenser temperature temp. is more

than setting value, the compressor will stop.

8.4.2.5 Evaporator temperature protection

When Evaporator temperature temp.is less

than setting value, the compressor will stop.

8.4.3 Heating Mode

8.4.3.1 Compressor running rules

When T1-Ts>-ΔT, the compressor will stop,

when T1-TS<ΔT-1.5 时，the compressor will be

on.

ΔT is the programmed parameter of

temperature compensation.

When the AC run in mute mode, the

compressor will run with low frequency.

When the current is more than setting value,

the current protection function will be activated

and the compressor will stop.

8.4.3.2 Outdoor fan running rules

The outdoor unit will be run at different fan

speed according to T4.

For different outdoor units, the fan speeds are

different

T 4

A +

8.4.3.3 Indoor fan running rules

When the compressor is on, the indoor fan can

be set to high/med/low/auto/mute.

When indoor unit coil temp. is low, the anti-cold

air function will start and indoor fan motor will

run at low speed, the speed can’t be

changed ,when the temp. is lower than setting

value, the indoor fan motor will stop.

When the indoor temp reaches the setting

temp., the compressor will stop, the indoor fan

motor will run at the minimum speed or setting

speed.(The anti-cold air function is valid).

The indoor fan is controlled as below:

Setting fan

speed

Actual fan speed

H（=H）

H+(H+=H+G)

M(M=M)

M+(M+=M+Z)

L(L=L)

L+(L+=L+D)

H-（H-=H-G)

M-(M-=M-Z)

L-(L-=L-D)

T1-Td

℃

Auto fan action in heating mode:

T 1 -T d + Δ T

8.4.3.4Defrosting mode

AC will enter the defrosting mode according to

the value of temp. of T3 and the value range of

temp. change of T3 and also the compressor

running time.

During the defrosting mode, the compressor

keep running, indoor and outdoor motor will stop,

defrost lamp of the indoor unit will be lighted

“ .” Will be displayed.

8.4.3.5 Evaporator coil temperature

protection

Resume

Off

Decrease

Hold

When evaporator temperature temp. is more

than the setting protection value, the

compressor will stop.

8.4.4 Auto-mode

This mode can be chosen with remote

controller and the setting temperature can be

changed between 17°C~30°C

In auto mode, the machine will choose cooling,

heating or fan-only mode according to ΔT (ΔT

=T1-Ts).

T1-Ts

Cooling

Heating*

Fan only

Heating*: For cooling only models, they will run

at fan speed

Indoor fan will run at auto fan of the relevant

mode.

The louver operates same as in relevant mode.

If the machine switches mode between heating

and cooling, the compressor will keep stopping

for certain time and then choose mode

according to T1-Ts.

If the setting temperature is modified, the

machine will choose running function again.

8.4.5 Drying mode

Indoor fan speed is fixed at breeze and can’t be

changed. The louver angle is the same as in

cooling mode.

All protections are active and the same as that

in cooling mode.

8.4.6 Forced operation function

Forced cooling mode:

The compressor and outdoor fan keep running

and the indoor fan runs at low speed. After

running for 30 minutes, AC will turn to auto mode with 24℃ setting temperature.

Forced auto mode:

The action of forced auto mode is the same as normal auto mode with 24℃ setting

temperature.

When AC receives signals, such as switch on,

switch off, timer on, timer off, mode setting, fan

speed setting, sleeping mode setting, follow me

setting, it will quit the forced operation.

8.4.7 Auto-Restart function

The indoor unit is equipped with auto-restart

function, which is carried out through an

auto-restart module. In case of a sudden power

failure, the module memorizes the setting

conditions before the power failure. The unit will

resume the previous operation setting (not

including swing function) automatically after

certain time when power returns.

If the memorization condition is forced cooling

mode, the unit will run in cooling mode for certain time and turn to auto mode as 24℃

setting temp.

If AC is off before power off and AC is required

to start up now, the compressor will have 1

minute delay when power on. Other conditions,

the compressor will have 3 minutes delay when

restarts.

8.4.8 8℃ Heating(optional)

When the compressor is running, the indoor fan

motor will run without anti-cold air function.

When the compressor is off, the indoor fan

motor is off .

8.4.9 Point check function

Press the LED DISPLAY or LED or MUTE button of the remote controller three times, and then press

the AIR DIRECTION or SWING button three times in ten seconds, the buzzer will keep ring for two

seconds. The air conditioner will enter into the information enquiry status. You can press the LED

DISPLAY or AIR DIRECTION button to check the next or front item’s information.

When the AC enter the “information enquiry” status, it will display the code name

in 2 seconds, the

details are as follows.

Enquiry information Displaying code Meaning

T1 T1 T1 temp.

T2 T2 T2 temp.

T3 T3 T3 temp.

T4 T4 T4 temp.

T2B Tb T2B temp.

TP TP TP temp.

TH TH TH temp.

Targeted Frequency FT Targeted Frequency

Actual Frequency Fr Actual Frequency

Indoor fan speed IF Indoor fan speed

Outdoor fan speed OF Outdoor fan speed

EXV opening angle LA EXV opening angle

Compressor continuous running time CT Compressor continuous

running time

Causes of compressor stop. ST Causes of compressor

stop.

Reserve A0

Reserve

When the AC enter into the information enquiry status, it will display the code value in the next 25s

, the

details are as follows.

Enquiry

information

Display value Meaning Remark

T1,T2,T3,T4,

T2B,TP,TH,

Targeted

Frequency,

Actual

Frequency

-1F,-1E,-1d,-1c,-

1b,-1A

-25,-24,-23,-22,-21,-20 1. All the displaying temperature is actual

value.

2. All the temperature is °C no matter what

kind of remote controller is used.

3. T1,T2,T3,T4,T2B display range:-25~70,

TP display range:-20~130.

4. Frequency display range: 0~159HZ.

5. If the actual value exceeds the range, it

will display the maximum value or minimum

value.

-19—99 -19—99

A0,A1,…A9 100,101,…109

b0,b1,…b9 110,111,…119

c0,c1,…c9 120,121,…129

d0,d1,…d9 130,131,…139

E0,E1,…E9 140,141,…149

F0,F1,…F9 150,151,…159

Indoor fan

speed

/Outdoor fan

speed

0 OFF

1,2,3,4 Low speed, Medium

speed, High speed,

Turbo

For some big capacity motors.

14-FF Actual fan

speed=Display value

turns to decimal

value and then

multiply 10. The unit

is RPM.

For some small capacity motors,

display value is from 14-FF(hexadecimal),

the corresponding fan speed range is from

200-2550RPM.

EXV opening

angle

0-FF Actual EXV opening

value=Display value

turns to decimal

value and then

multiply 2.

Compressor

continuous

running time

0-FF 0-255 minutes If the actual value exceeds the

range, it will display the maximum

value or minimum value.

Causes of

compressor

stop.

0-99 For the detailed

meaning, please

consult with engineer

Decimal display

Reserve 0-FF

+ 63 hidden pages

Midea MEHS-12PSH1, MEHSU-12PHH2, MEHSU-09PHH2, MEHSU-24PHH2, MEHS-30PSH2 Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual