Midea MS9V-18HRDN1-QC2(B) 9V SERIES User manual

9VSI-1010-A
SERVICE MANUAL
MIDEA AIRCONDITIONER
DC INVERTER
SPLIT WALL-MOUNTED TYPE
MS9V-18HRDN1-QC2(B)
MS9V-24HRDN1-QC2W
9V SERIES

CONTENTS
1. Precaution .................................................................................................................................................... 1
1.1 Safety Precaution..........................................................................................................................1
1.2 Warning.........................................................................................................................................1
2. Function........................................................................................................................................................ 6
3. Dimension .................................................................................................................................................... 8
3.1 Indoor Unit.....................................................................................................................................8
3.2 Outdoor Unit................................................................................................................................10
4. Refrigerant Cycle Diagram ........................................................................................................................11
5. Wiring Diagram .......................................................................................................................................... 12
5.1 Indoor..........................................................................................................................................12
5.2 Outdoor Unit................................................................................................................................13
6. Installation details...................................................................................................................................... 14
6.1 Wrench torque sheet for installation...........................................................................................14
6.2 Connecting the cables ................................................................................................................14
6.3 Pipe length and the elevation .....................................................................................................14
6.4Air purging with vacuum pump....................................................................................................15
6.5 Pumping down (Re-installation)..................................................................................................16
6.6 Re-air purging (Re-installation)...................................................................................................18
6.7 Balance refrigerant of the 2-way, 3-way valves.......................................................................... 19
6.8 Evacuation ..................................................................................................................................20
6.9 Gas charging...............................................................................................................................21
7. Operation characteristics ......................................................................................................................... 22
8. Electronic function.................................................................................................................................... 23
8.1 Abbreviation ................................................................................................................................23
8.2 Display function...........................................................................................................................23
8.3 Main Protection...........................................................................................................................24
8.4 Operation Modes and Functions.................................................................................................25
9. Troubleshooting......................................................................................................................................... 37
9.1 Indoor Unit Error Display.............................................................................................................38
9.2 Diagnosis and Solution...............................................................................................................39

1
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 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.

2
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.
There is risk of fire, electric shock, explosion, or injury.
Do not install the product on a defective installation stand.
It may cause injury, accident, or damage to the product.
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.
Moisture may condense and wet or damage furniture.
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.
There is risk of fire or electric shock.
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 electric 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

3
turn the product on.
Do not use the telephone or turn switches on or off.
There is risk of explosion or fire.
If strange sounds, or small 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 (flooded or submerged), 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.

4
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.
To avoided 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.
Avoid personal injury.
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 periods of time. (Do not sit in the
draft).
This could harm to your health.
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.
It may cause product failure.
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.
There is risk of personal injury.
Do not step on or put anything on the product. (outdoor units)
There is risk of personal injury and failure of product.
Always insert the filter securely. Clean the filter every two weeks or more often if

5
necessary.
A dirty filter reduces the efficiency of the air conditioner and could cause product malfunction or
damage.
Do not insert hands or other object through air inlet or outlet while the product is
operated.
There are sharp and moving parts that could cause personal injury.
Do not drink the water drained from the product.
It is not sanitary could cause serious health issues.
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 mew 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.
The chemical in batteries could cause burns or other health hazards

6
2. Function
Indoor unit
Operation by remote controller
Sensing by room temperature
Room temperature control
Anti-freezing control in cooling
Time Delay Safety control
Indoor fan speed control
Two-direction air vane
Sleep mode auto control
Independent dehumidification
Air flow Direction control
Anti-cold function
Room temperature sensor.
Pipe temperature sensor.
Maintain the room temperature in accordance with
the setting temperature.
Prevent the water being frozen on evaporator by sensing
the evaporator pipe temperature in cooling mode
Restarting is for approx. 3 minutes..
Auto Restart Function
high, med, low, auto.
The unit will decide the louver direction according
to operation mode.
The fan is turn to low speed (cooling/heating).
The function is usually used in rainy days in
springtime or damp areas.
The louver can be set at the desired position
or swing up and down automatically
Self-diag. function
Timer function
Follow me
Self-cleaning
Temp. Compensation
Auto mode
The mode can be change by the room
temperature.
Prevent the cold wind at the beginning of unit
start.
Auto defrost
Flexible wiring connection
When the power supply is interrupted and then
restore, the air conditioners automatically
restore the previous function setting
Ionizer (Optional)
Indoor golden fin (optional)

7
.
It protects the valves and prevents water from dripping.
The unit has 3 min delay between continuously ON/OFF operations.
Outdoor unit
Power relay control
The hydrophilic fin can improve the heating efficiency at operation mode.
Hydrophilic aluminum fin
It is only operated in the heating operation mode except defrosting operation.
Anti-rust cabinet
Valve protection cover
4 way valve control
Made from electrolytic zinc steel sheet and anti-rust coated components.
Low noise air flow system
Bird tail propeller fan makes the outdoor unit run more quietly.
Discharge pipe temperature protect
Chassis heating belt (Optional)
Driving heating at -15
℃

8
3. Dimension
3.1 Indoor Unit
Dimension
Mode
W H D
MS9V-18HRDN1-QC2(B)
995
295
200
MS9V-24HRDN1-QC2W
1084
320
221
MS9V-18HRDN1-QC2(B)

9
MS9V-24HRDN1-QC2W
：

10
3.2 Outdoor Unit
MOC2-18HDN1-QC2
MOF-24HDN1-QC2W
Dimension Mode
W
D
H
W1
A
B
18K
760
285
590
823
530
290
Dimension Mode
W
D
H
W1
A
B
24K 845 335 695 918 560 335

11
4. Refrigerant Cycle Diagram

12
5. Wiring Diagram
5.1 Indoor
MS9V-18HRDN1-QC2(B)
MS9V-24HRDN1-QC2

13
5.2 Outdoor Unit
MOC2-18HDN1-QC2
MOF-24HDN1-QC2W

14
6. Installation details
6.1 Wrench torque sheet for installation
Outside diameter Torque Additional tightening torque
mm
inch
N
·
cm
N
·
cm
Ф6.35 1/4 1500
(153kgf.cm) 1600 (163kgf.cm)
Ф9.53 3/8 2500
(255kgf.cm) 2600 (265kgf.cm)
Ф12.7 1/2 3500
(357kgf.cm) 3600 (367kgf.cm)
Ф16 5/8 4500
(459kgf.cm) 4700 (479kgf.cm)
6.2 Connecting the cables
The power cord of connect should be selected according to the following specifications sheet.
Grade
Unit 18K 24K
mm22.5 2.5
6.3 Pipe length and the elevation
Capacity
Btu/h
Pipe size Standard
length
(m)
Max.
Elevation
B (m)
Max.
Length
A (m)
Additional
refrigerant
(g/m)
Gas Liquid
18K 1/2’’(Ф12.7) 1/4"(Ф6.4) 5 10 25 20
24K 5/8’’(Ф16) 3/8’’(Ф9.53) 5 10 25 40

15
Caution:
Capacity is base on standard length and maximum allowance length is base of reliability.
Oil trap should be installed per 5-7 meters.
6.4 Air purging with vacuum pump
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.
Air purging with vacuum pump
(Indoor unit) (Liquid side)
(Gas side)
Vacuum
pump
Vacuum
pump
adaptor
Lo Hi
Handle Hi
Two-way valve
Close
Manifold valve
Compound meter Pressure
gauge
-76cmHg
Handle Lo
Charge hose Charge hose
(Outdoor unit)
Close
Three-way valve

16
1. Completely tighten the flare nuts of the indoor and outdoor units, connect the manifold valve charge.
2. Connect the charge hose connection to the vacuum pump.
3. Fully open the handle Lo of the manifold valve.
4. Operate the vacuum pump to evacuate. After starting evacuation, slightly loose the flare nut of the Lo valve
on the gas pipe side and check the air is entering. (Operation noise of the vacuum pump changes and a
compound meter indicates 0 stead of minutes)
5. After the evacuation is complete, fully close the handle Lo valve of the manifold valve and stop the
operation of the vacuum pump. Make evacuation for 15 minutes or more and check the compound meter
indicates -76cmHg.
6. Turn the stem of the Hi valve 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.
7. Remove the charge hose from the Lo pressure charge hose.
8. Fully open the Hi and Lo packed valve.
9. Securely tighten the cap of the packed valve.
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.
6.5 Pumping down (Re-installation)

17
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. Operate the unit for 10 to 15 minutes.
3. Stop operation and wait for 3 minutes, then connect the charge set to the service port of the 3-way
valve.
Connect the charge hose with the push pin to the gas service port.
5.Air purging of the charge hose.
Open the low-pressure valve on the charge set slightly to purge air from the charge hose.
6. Set the 2-way valve to the close position.
7. Operate the air conditioner at the cooling cycle and stop it when the gauge indicates 0.1MPa.
8. Immediately set the 3-way valve to the closed position.
Do this quickly so that the gauge ends up indicating 0.3 to 0.5Mpa.
Disconnect the charge set, and amount the 2-way and 3-way valve’s stem nuts and service port
caps.
Use a torque wrench to tighten the service port cap.
Be sure to check for gas leakage.

18
6.6 Re-air purging (Re-installation)
Procedure:
1. Confirm that both the 2-way and 3-way valves are set to the closed position.
2. Connect the charge set and a charging cylinder to the service port of the 3-way valve.
Leave the valve on the charging cylinder closed.
3.Air purging.
Open the valves on the charging cylinder and the charge set. Purge the air by loosening the flare nut
on the 2-way valve approximately 45’ for 3 seconds then closing it for 1 minute; repeat 3 times.
After purging the air, use a torque wrench to tighten the flare nut to on the 2-way valve.
4. Check the gas leakage.
Check the flare connections for gas leakage.
5. Discharge the refrigerant.
Close the valve on the charging cylinder and discharge the refrigerant until the gauge indicates 0.3
to 0.5 Mpa.
6. Disconnect the charge set and the charging cylinder, and set the 2-way and 3-way valves to the
open position.