Midea M2OC-18HFN1-M User manual

Multi outdoor units
SERVICE MANUAL
Multi zone
CONDENSING UNITS
Revision B: ODMI-C1-1403
Model Numbers:
M2OC-18HFN1-M M3OC-30HRFN1-M
M2OD-18HFN1-M M4OC-36HRFN1-M
M3OD-27HRDN1-M
WARNING
Installation MUST conform with local building codes or, in the absence of local
codes, with the National Electrical Code NFPA70/ANSI C1-1993 or current edition
and Canadian Electrical Code Part1 CSA C.22.1.
The information contained in the manual is intended for use by a qualified service
technician familiar with safety procedures and equipped with the proper tools and
test instruments
Installation or repairs made by unqualified persons can result in hazards to you
and others.
Failure to carefully read and follow all instructions in this manual can result in
equipment malfunction, property damage, personal injury and/or death.
Table of Contents
1. Product Specifications
2. Indoor Unit Combination
3. Suggested Indoor Unit Model Numbers
4. Dimension Of Outdoor Unit
5. Refrigerant Cycle Diagram
6. Installation Details
7. Electronic Function
8. Wiring Diagrams And Electrical Trouble Shooting
9. Disassembly Instructions
10. Exploded View

CONTENTS
1. Indoor Unit Combination .......................................................................................................................................... 4
2. Suggested Indoor Unit Model Numbers ................................................................................................................... 6
3. Dimension Of Outdoor Unit...................................................................................................................................... 7
4. Refrigerant Cycle Diagram ........................................................................................................................................ 8
5. Installation Details .................................................................................................................................................... 9
6.1 Wrench torque sheet for installation ................................................................................................................. 9
6.2 Connecting the cables ........................................................................................................................................ 9
6.3 Pipe length and the elevation............................................................................................................................. 9
6.4 Installation for the first time .............................................................................................................................. 9
6.5 Adding the refrigerant after running the system for many years .................................................................... 11
6.6 Re-installation while the indoor unit need to be repaired...............................................................................11
6.7 Re-installation while the outdoor unit need to be repaired ............................................................................12
6. Electronic Function ................................................................................................................................................. 13
7.1 Abbreviation ..................................................................................................................................................... 13
7.2 Electric control working environment.............................................................................................................. 13
7.3 Main Protection................................................................................................................................................ 13
7.4 Control and Functions ......................................................................................................................................15
7. Wiring Diagrams......................................................................................................................................................19
8. Troubleshooting......................................................................................................................................................32
9.1Safety................................................................................................................................................................. 32
8.2 Indoor Unit Error Display............................................................................................................................. 33
9.3 Outdoor Unit Display ........................................................................................................................................36
9.4 Diagnosis and Solution ..................................................................................................................................... 40
9.5 Trouble Criterion Of Main Parts. ......................................................................................................................89
9. Disassembly Instructions ......................................................................................................................................100
Model: M2OC-18HFN1-M, M2OD-18HFN1-M (W210 metal plate)..................................................100

Model: M3OD-27HRDN1-M (W210 metal plate).................................................................................106
Model: M3OC-30HRFN1-M (W310 metal plate)..................................................................................113
Model: M4OC-36HRFN1-M (W520 metal plate)..................................................................................121

1. Indoor Unit Combination
Multi DC
Outdoor Unit
Nominal
capacity
Suggested
Combination
Limit
1drive 2(M2OC)
5.2kW
7
None
9
12
7+9
7+12
9+9
9+12
Multi DC
Outdoor Unit
Nominal
capacity
Suggested
Combination
Limit
1drive 2(M2OD)
5.2kW
7
None
9
12
7+9
7+12
9+9
9+12
12+12
Multi DC
Outdoor Unit
Nominal
capacity
Suggested
Combination
Limit
1 drive 3(27K)
7.5kW
7
The 18k indoor
unit should not
be Floor Ceiling
or Duct unit;
There should be
only one Floor
Ceiling, Oasis or
Duct unit;
9
12
18
7+7
7+9
7+12
7+18
9+9
9+12
9+18
12+12
12+18
7+7+7
7+7+9
7+7+12
7+7+18
7+9+9
7+9+12
7+9+18
7+12+12
9+9+9
9+9+12
9+12+12
Multi DC
Outdoor Unit
Nominal
capacity
Suggested
Combination
Limit
1 drive 3(30K)
8.0kW
7
There should be
only one Floor
Ceiling or Duct
unit;
9
12
18
7+7
7+9
7+12
7+18
9+9
9+12
9+18
12+12
12+18
18+18
7+7+7
7+7+9
7+7+12
7+7+18
7+9+9
7+9+12
7+9+18
7+12+12
7+12+18
9+9+9
9+9+12
9+9+18
9+12+12
9+12+18
12+12+12
Multi DC
Outdoor Unit
Nominal
capacity
Suggested
Combination
Limit
1 drive 4(36K)
10.5kW
7
None
9
12
18

7+7
7+9
7+12
7+18
9+9
9+12
9+18
12+12
12+18
18+18
7+7+7
7+7+9
7+7+12
7+7+18
7+9+9
7+9+12
7+9+18
7+12+12
7+12+18
9+9+9
9+9+12
9+9+18
9+12+12
9+12+18
9+18+18
12+12+12
12+12+18
12+18+18
7+7+7+7
7+7+7+9
7+7+7+12
7+7+7+18
7+7+9+9
7+7+9+12
7+7+9+18
7+9+9+9
7+9+9+12
7+9+9+18
7+9+12+12
7+9+12+18
7+12+12+12
7+12+12+18
9+9+9+9
9+9+9+12
9+9+9+18
9+9+12+12
9+9+12+18
9+12+12+12
9+12+12+18
12+12+12+12

3. Suggested Indoor Unit Model
Numbers
SUGGESTED INDOOR
M2OC-18HFN1-M
7K
MS9AI-07HRDN1-M
9K
MS9AI-09HRDN1-M(A)
MSV1I-09HRDN1-M
12K
MSV1I-12HRDN1-M
MS9AI-12HRDN1-M
MTBI-12HWDN1-M
MTBU-12HRDN1-M
MFAI-12HRDN1-M
MFAU-12HRFN1-M
MCA2I-12HRDN1-M
MCA2U-12HRFN1-M
MUBI-12HRDN1-M
MUBU-12HRFN1-M
SUGGESTED INDOOR
M2OD-18HFN1-M
7K
MS9AI-07HRDN1-M
9K
MS9AI-09HRDN1-M(A)
MSV1I-09HRDN1-M
MS11M-09HRFN1-MX4W
MS11M-09HRFN1-MX4W
12K
MSV1I-12HRDN1-M
MS9AI-12HRDN1-M
MS11M-12HRFN1-MV0W
MTBI-12HWDN1-M
MTBU-12HRDN1-M
MFAI-12HRDN1-M
MFAU-12HRFN1-M
MCA2I-12HRDN1-M
MCA2U-12HRFN1-M
MUBI-12HRDN1-M
MUBU-12HRFN1-M
MS11M-12HRFN1-MW0W
MS11M-12HRFN1-MV0W
SUGGESTED INDOOR
M3OD-27HRDN1-M
7K
MS9AI-07HRDN1-M
9K
MS9AI-09HRDN1-M(A)
MSV1I-09HRDN1-M
12K
MSV1I-12HRDN1-M
MS9AI-12HRDN1-M
MTBI-12HWDN1-M
MTBU-12HRDN1-M
MFAI-12HRDN1-M
MFAU-12HRFN1-M
MCA2I-12HRDN1-M
MCA2U-12HRFN1-M
MUBI-12HRDN1-M
MUBU-12HRFN1-M
18K
MSV1I-18HRDN1-M
MS9AI-18HRDN1-M
MCA2I-18HRDN1-M
MCA2U-18HRFN1-M
SUGGESTED INDOOR
M3OC-30HRFN1-M
7K
MS9AI-07HRDN1-M
9K
MS9AI-09HRDN1-M(A)
MSV1I-09HRDN1-M
MS11M-09HRFN1-MX4W
MS11M-09HRFN1-MW0W
12K
MSV1I-12HRDN1-M
MS9AI-12HRDN1-M
MS11M-12HRFN1-MV0W
MS11M-12HRFN1-MW0W
MTBI-12HWDN1-M
MTBU-12HRDN1-M
MFAI-12HRDN1-M
MFAU-12HRFN1-M
MCA2I-12HRDN1-M
MCA2U-12HRFN1-M
MUBI-12HRDN1-M
MUBU-12HRFN1-M
18K
MSV1I-18HRDN1-M
MS9AI-18HRDN1-M
MS11M-18HRFN1-MU0W
MTBI-18HWDN1-M
MTBU-18HRDN1-M
MCA2I-18HRDN1-M
MCA2U-18HRFN1-M
MUBI-18HRDN1-M
MUBU-18HRFN1-M
SUGGESTED INDOOR
M4OC-36HRFN1-M
7K
MS9AI-07HRDN1-M
9K
MS9AI-09HRDN1-M(A)
MSV1I-09HRDN1-M
MS11M-09HRFN1-MX4W
MS11M-09HRFN1-MW0W
12K
MSV1I-12HRDN1-M
MS9AI-12HRDN1-M
MS11M-12HRFN1-MV0W
MS11M-12HRFN1-MW0W
MTBI-12HWDN1-M
MTBU-12HRDN1-M
MFAI-12HRDN1-M
MFAU-12HRFN1-M
MCA2I-12HRDN1-M
MCA2U-12HRFN1-M
MUBI-12HRDN1-M
MUBU-12HRFN1-M
18K
MSV1I-18HRDN1-M
MS9AI-18HRDN1-M
MS11M-18HRFN1-MU0W
MTBI-18HWDN1-M
MTBU-18HRDN1-M
MCA2I-18HRDN1-M
MCA2U-18HRFN1-M
MUBI-18HRDN1-M
MUBU-18HRFN1-M

4. Dimension Of Outdoor Unit
Model
Dimension (mm(in.))
W
D
H
W1
A
B
M2OC-18HFN1-M
845(33.3)
320(12.6)
700(27.6)
908(35.7)
560(22)
335(13.2)
M2OD-18HFN1-M
M3OD-27HRDN1-M
M3OC-30HRFN1-M
900(35.4)
315(12.4)
860(33.9)
980(38.6)
590(23.2)
333(13.1)
M4OC-36HRFN1-M
990(39)
345(13.6)
965(38)
1075(42.3)
624(24.6)
366(14.4)

5. Refrigerant Cycle Diagram
5.1Refrigeration circuit drawing of inverter dual zone
LIQUID VALVE A
GAS VALVE A
HEAT
EXCHANGE
(EVAPORATOR) HEAT
EXCHANGE
(CONDENSER)
Compressor
4-WAY VALVE
COOLING
HEATING
T2 Evaporator
temp. sensor
middle
T1 Room
temp. sensor
T3
Condenser
temp. sensor
T5 Discharge
temp. sensor
T4 Ambient
temp. sensor
INDOOR OUTDOOR
EXV A CAPILIARY A
CHECK VALVE
CAPILIARY TUBE
EXV B CAPILIARY B
LIQUID VALVE B
GAS VALVE B
Accumulator
T2B-A Evaporator
temp. sensor outlet
T2B-B
5.2 Refrigeration circuit drawing of inverter tri-zone
LIQUID VALVE A
GAS VALVE A
HEAT
EXCHANGE
(EVAPORATOR) HEAT
EXCHANGE
(CONDENSER)
Compressor
4-WAY VALVE
COOLING
HEATING
T2 Evaporator
temp. sensor
middle
T1 Room
temp. sensor
T3
Condenser
temp. sensor
T5 Discharge
temp. sensor
T4 Ambient
temp. sensor
INDOOR OUTDOOR
EXV A CAPILIARY A
CHECK VALVE
CAPILIARY TUBE
EXV B CAPILIARY B
LIQUID VALVE B
GAS VALVE B
EXV C CAPILIARY C
LIQUID VALVE C
GAS VALVE C Accumulator
T2B-A Evaporator
temp. sensor outlet
T2B-B
T2B-C
5.3 Refrigeration circuit drawing of inverter qua-zone
LIQUID VALVE A
GAS VALVE A
HEAT
EXCHANGE
(EVAPORATOR) HEAT
EXCHANGE
(CONDENSER)
Compressor
4-WAY VALVE
COOLING
HEATING
T2 Evaporator
temp. sensor
middle
T1 Room
temp. sensor
T3
Condenser
temp. sensor
T5 Discharge
temp. sensor
T4 Ambient
temp. sensor
INDOOR OUTDOOR
EXV A CAPILIARY A
CHECK VALVE
CAPILIARY TUBE
EXV B CAPILIARY B
LIQUID VALVE B
GAS VALVE B
EXV C CAPILIARY C
LIQUID VALVE C
GAS VALVE C
EXV D CAPILIARY D
LIQUID VALVE D
GAS VALVE D
Accumulator High pressure
switch
Low pressure
switch
T2B-A Evaporator
temp. sensor outlet
T2B-B
T2B-C
T2B-D

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)
Ф9.52
3/8
2500(255kgf.cm)
2600(265kgf.cm)
Ф12.7
1/2
3500(357kgf.cm)
3600(367kgf.cm)
6.2 Connecting the cables
The power cord connection should be
selected according to the following
specifications sheet.
Unit
AWG
Dual-zone(18K outdoor unit)
14
Tri-zone (27K/30K outdoor unit).
14
Quad-zone(36K outdoor unit)
12
For indoor unit and outdoor unit connection
line, 16AWG is ok for all.
6.3 Pipe length and the elevation
Maximum piping length and height difference
1 drive 2
1 drive 3
1 drive 4
Max. length for all rooms
(m)
30(98ft)
45(150ft)
60(200ft)
Max. length for one IU (m)
20(65.6ft)
25(82ft)
30(98ft)
Max. height
difference
between IU
and OU (m)
OU
higher
than IU
10(33ft)
10(33ft)
10(33ft)
OU lower
than IU
15(49.2ft)
15(49.2ft)
15(49.2ft)
Max. height difference
between IUs (m)
10(33ft)
10(33ft)
10(33ft)
Additional refrigerant charge
1 drive 2
1 drive 3
1 drive 4
Chargeless pipe
length (m)
15(49.2ft)
22.5(73.8ft)
30(98.4ft)
Additional
refrigerant
charge
g
15 x (length
for all rooms -
15)
15 x (length
for all rooms –
22.5)
15 x (length
for all rooms -
30)
oz
(.0.161
x(length for all
rooms –
49.2))
(.0.161
x(length for all
rooms –
73.8))
(.0.161x(lengt
h for all rooms
–98.4))
Caution:
●Refrigerant pipe diameter is different
according to indoor unit to be connected.
When using the extension pipe, refer to the
tables below.
●When refrigerant pipe diameter is different
from that of outdoor unit union (for 18K indoor
unit), additional transfer connector needs to
be used on outdoor unit union.
Indoor unit
Extension pipe diameter
(mm/inch)
Model
Pipe diameter
(mm/inch)
9K
Liquid
6.35(1/4)
Liquid
6.35(1/4)
Gas
9.52(3/8)
Gas
9.52(3/8)
12K 18K
Liquid
6.35(1/4)
Liquid
6.35(1/4)
Gas
12.7(1/2)
Gas
12.7(1/2)
Outdoor unit union diameter (mm/inch)
Indoor unit A/B/C/D
Liquid
6.35(1/4)
Gas
9.52(3/8)
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.
2. Air purging by refrigerant
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.
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 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 by loosening the flare
nut on the 2-way valve approximately 45’ until the
gauge indicates 0.3Mpa(43.5Psi) to 0.5
Mpa(72.5Psi)..
6). Disconnect the charge set and the charging
cylinder, and set the 2-way and 3-way valves to
the open position.
Be sure to use a hexagonal wrench to operate the
valve stems.
7). Mount the valve stems nuts and the service port
cap.
Be sure to use a torque wrench to tighten the
service port cap to a torque 18N·m.
Be sure to check the gas leakage.
3. Adding refrigerant if the pipe length
exceeds chargeless pipe length

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 the 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 table), disconnect the charge
hose from the 3-way valve’s service port
immediately and turn off the air conditioner
7). Mount the valve stems nuts and the service port
cap.
Be sure to use a torque wrench to tighten the
service port cap to a torque 18N·m.
Be sure to check the gas leakage.
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 by the refrigerant
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 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 by loosening the flare
nut on the 2-way valve approximately 45’ until the
gauge indicates 0.3Mpa(43.5Psi) to 0.5
Mpa(72.5Psi)..
6). Disconnect the charge set and the charging
cylinder, and set the 2-way and 3-way valves to
the open position
Be sure to use a hexagonal wrench to operate the
valve stems.
7). Mount the valve stems nuts and the service port
cap
Be sure to use a torque wrench to tighten the
service port cap to a torque 18N.m.
Be sure to check the gas leakage.
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. Electronic Function
7.1 Abbreviation
T1: Indoor ambient temperature
T2: Coil temperature of indoor heat exchanger
middle.
T2B: Coil temperature of indoor heat exchanger
outlet.
T3: Pipe temperature of outdoor heat exchanger
T4: Outdoor ambient temperature
Tp: Compressor discharge temperature
7.2 Electric control working environment.
7.2.1 Input voltage: 230V.
7.2.2 Input power frequency:60Hz.
7.2.3 Indoor fan normal working amp. is less than
1A.
7.2.4 Outdoor fan. Normal working amp. is less
than 1.5A.
7.2.5 Four-way valve normal working amp. is less
than 1A.
7.3 Main Protection
7.3.1 Three Minutes Delay at restart for
compressor.
---- 1min delay for the 1st time start-up and 3
minutes delay for others.
7.3.2 Temperature protection of compressor
discharge.
When the compressor discharge temp. is getting
higher, the running frequency will be limited as
below rules:
----If 102℃<Tp<115℃, decrease the frequency to
the lower level every 2 minutes till to F1.
---If Tp>115℃for 10 seconds, the compressor
will stop and restart till Tp<90℃.
7.3.3 Fan Speed is out of control(DC fan
motor).

---- When outdoor fan speed is lower than
300RPM or higher than 2400RPM for 60 second,
the whole unit stops and LED displays failure.
7.3.4 Inverter module Protection.
----Inverter module protection itself has a
protection function against current, voltage and
temperature. If these protections happened, the
corresponding code will display on indoor unit
LED and A/C will stop. The unit will recover 3min
delay after the protection disappeared.
7.3.5 Low voltage protection
VOLT_RST1_ADD
VOLTAGE
No limit
VOLT_LTM1_ADD
VOLT_RST2_ADD
VOLT_LTM2_ADD
VOLT_LTM_FREQ1_ADD
VOLT_LTM_FREQ2_ADD
Note: if the low voltage protection occurs and not
resumes within 3min, it will keep the protection
always after restart the machine.
7.3.6 Compressor current limit protection
If the compressor current exceeds the current
limit value for 10 seconds, the compressor
frequency will be limited as below table.
Cooling mode:
Current
frequency(Hz)
Current limit
value(A)
Frequency limit
COOL_F16
ICOOLLMT12
Decrease the frequency to
COOL_F4 and run at COOL_F4
for 3 minutes.
After that, the frequency will be
adjusted according to the capacity
demand and rise to the upper
level every 3 minutes
(When the frequency>COOL_F4
via capacity demand).
COOL_F15
ICOOLLMT11
COOL_F14
ICOOLLMT10
COOL_F13
ICOOLLMT9
COOL_F12
ICOOLLMT8
COOL_F11
ICOOLLMT7
COOL_F10
ICOOLLMT6
COOL_F9
ICOOLLMT5
COOL_F8
ICOOLLMT4
COOL_F7
ICOOLLMT3
COOL_F6
ICOOLLMT2
COOL_F5
ICOOLLMT1
If the current frequency is lower than COOL_F4, the frequency will
not be limited.
After 10s of the compressor start, if the current>ICOOL, the AC will
display the failure for 30 seconds and stop. The AC will restart 3
minutes later.
Heating mode:
Current
frequency(Hz)
Current limit
value(A)
Frequency limit
HEAT_F16
IHEATLMT12
Decrease the frequency to
HEAT_F4 and run at HEAT_F4 for
3 minutes.
After that, the frequency will be
adjusted according to the capacity
demand and rise to the upper
level every 3 minutes
(When the frequency>Heat_F4 via
capacity demand).
HEAT_F15
IHEATLMT11
HEAT_F14
IHEATLMT10
HEAT_F13
IHEATLMT9
HEAT_F12
IHEATLMT8
HEAT_F11
IHEATLMT7
HEAT_F10
IHEATLMT6
HEAT_F9
IHEATLMT5
HEAT_F8
IHEATLMT4
HEAT_F7
IHEATLMT3
HEAT_F6
IHEATLMT2
HEAT_F5
IHEATLMT1
If the current frequency is lower than HEAT_F4, the frequency will
not be limited.
After 10s of the compressor start, if the current>IHEAT, the AC will
display the failure for 30 seconds and stop. The AC will restart 3
minutes later.
7.3.7 Indoor / outdoor units communication
protection
If the indoor units cannot receive the feedback
signal from the outdoor units for 2 minutes, the
AC will stop and display the failure.
7.3.8 High condenser coil temp. protection.
When T3>65℃for 3 seconds, the compressor
will stop while the indoor fan and outdoor fan will
continue.
When T3<52℃, the protection will release and
the compressor will restart after 3 minutes.
7.3.9 Outdoor unit anti-freezing protection
When T2B<0℃for 250 seconds, the indoor unit
capacity demand will be zero and resume to
normal when T2B>10℃.
7.3.10 Oil return
Running rules:

1.If the compressor frequency keeps lower than
RET_OIL_FREQ1_ADD for
RET_OIL_TIME1_ADD,the AC will rise the
frequency to RET_OIL_FREQ2_ADD for
RET_OIL_TIME2_ADD and then resume to
former frequency.
2.During the oil return process, the EXV will keep
300p while the indoor units will keep the current
running mode.
7.3.11 Compressor preheating functions
----Preheating permitting condition:
If T4(outdoor ambient temperature)＜3℃and
newly powered on or if T4＜3℃and compressor
has stopped for over 3 hours, the compressor
heating cable will work.
----Preheating mode:
A weak current flow through the coil of
compressor from the wiring terminal of
compressor, then the compressor is heated
without operation.
----Preheating release condition:
If T4＞5℃or the capacity demand isn’t zero,
preheating function will stop.
7.3.12 Compressor crankcase heater
----Preheating permitting condition:
①When T4<3 ℃within 5 seconds of being
plugged in, the crankcase heater will be
active.
②When T4<3℃and the compressor is not
running for 3 hours, the crankcase heater will
be active.
----Preheating release condition:
When T4≧5℃or the indoor has capacity
demand, the crankcase heater will stop work.
7.4 Control and Functions
7.4.1 Capacity Request Calculation
Total capacity Request=Σ(Norm code ×HP) /10×
modify rate+ correction
Cooling mode:
T1 Ts
3
1
1e
c
a4
2
0
2
3
01
f
d
b
Capacity area
a
b
c
d
e
f
Norm code (N)
3
2
1.5
1
0.5
0
Model
9K
12K
18K
HP
1.0
1.2
1.5
Note: The final result is integer.
Plus all the indoor capacity request together, then
modify it by T4
When there’s only one indoor unit
Cooling
Outdoor temperature (T4)
＞29℃
18℃~ 29℃
<17℃
Modify rate
100%
60%
40%
When there’re more than one indoor unit
Cooling
Outdoor temperature (T4)
＞25℃
17℃~ 25℃
<17℃
Modify rate
100%
80%
40%
Note: The final result is integer.
In low ambient cooling mode, modify rate is fixed
as 40%.
According to the final capacity request to
confirm the operating frequency, as following
table.
Frequency (Hz)
0
COO
L_F1
COO
L_F2
…
…
COOL
_F15
COO
L_F1
6
Amendatory
capacity
demand.
0
1
2
…
…
15
16

Meanwhile the maximum running frequency will
be adjusted according to the outdoor ambient
temp.
43
41
38 T4LimFre1_ADD
No limit
T4LimFre2_ADD
T4LimFre3_ADD
42
39
37
49
46 T4LimFre4_ADD
T4LimFre5_ADD
48
45
Heating mode
T1 Ts
4
0
a
3
1
-1
3
12
0
b
c
d
e
f
2
Capacity area
a
b
c
d
e
f
Norm code (N)
3
2
1.5
1
0.5
0
Model
9K
12K
18K
HP
1.0
1.2
1.5
Plus all the indoor capacity request together,
then modify it by T4
When there’s only one indoor unit
Heating
Outdoor temperature (T4)
＜0℃
＜12℃
12℃~ 17℃
≥17℃
Modify rate
120%
80%
40%
20%
When there’re more than one indoor unit
Heating
Outdoor temperature (T4)
＜0℃
＜12℃
12℃~ 17℃
≥17℃
Modify rate
120%
100%
80%
60%
Note: The final result is integer.
Then modify it according to T2
average(correction):
Note:Average value of T2：Sum T2 value of all
indoor units)/(indoor units number
According to the final capacity request to
confirm the operating frequency, as following
table.
Frequency (Hz)
0
HEAT
_F1
HEAT
_F2
…
HEAT
_F15
HEAT
_F16
Amendatory
capacity
demand.
0
1
2
…
15
16
Heating capacity improved in low ambient
heating
In heating mode, when
T2<T2_ExitT4LowFre_ADD , and T4<-4 ℃,
there’s frequency elevation:
elevated frequency= Recent frequency * 110%
When T2> T2_ExitT4LowFre_ADD-2 and T4>-6,
the highest frequency can’t exceed F17
When T2> T2_ExitT4LowFre_ADD-4 and T4>-8,
the highest frequency can’t exceed F18
When T2> T2_ExitT4LowFre_ADD-6 and T4>-10,
the highest frequency can’t exceed F19

In the other conditions, the highest frequency is
F20
7.4.2 Defrosting control
Condition of defrosting:
T3≦TempEnterDefrost_ADD ℃and lasts for 40
minutes.
Defrosting action：
off
on
Cool-F9
10S
30S
TimeA
10S
4-way valve
defrosting
Defrosting over
compressor
Indoor fan
Outdoor fan
EXV open
frequency
Max 10 minutes
frequency
Compressor stops
off
Anti-cold control
off
480P
480P for 240s
Condition of ending defrosting:
If any one of following items is satisfied,
defrosting will stop and the machine will turn to
normal heating mode.
①T3 > TempQuitDefrost_ADD ℃;.
②The defrosting time achieves 10min.
③Turn to other modes or off.
7.4.3 Outdoor fan control
7.4.3.1 Cooling mode
For M3OD-27HRDN1-M:
27
25
High
Low
When low ambient cooling is valid:
27 High
Low
25
20
15
low ambient cooling
For M2OC-18HFN1-M, M2OD-18HFN1-M,M3OC-
30HRFN1-M, M4OC-36HRFN1-M:
T4
ADC_FAN_HI_SPD_ADD
BDC_FAN_MID_SPD_ADD
CDC_FAN_MIN_SPD_ADD
DDC_FAN_SLOW_SPD_ADD
EDC_FAN_SSLOW_SPD_ADD
23℃
22℃
20℃
28℃
19℃
17℃
26℃
25℃
Outdoor fan speed control logical (low ambient
cooling)
When T4 <15 ℃and T3 < 30 ℃, the unit will
enter into low ambient cooling mode. The outdoor
fan will choose speed according to T3.
When T3≥38 ℃or when T4≥20 ℃, the outdoor
fan will choose the speed according to T4 again.

38
Exit low ambient cooling
mode,run with high fan
for 1 minute
Low
30
27
23
off
7.4.3.2 Heating mode
For M3OD-27HRDN1-M:
For M2OC-18HFN1-M,M2OD-18HFN1-M,M3OC-
30HRFN1-M, M4OC-36HRFN1-M:
T4
EDC_FAN_SSLOW_SPD_ADD
DDC_FAN_SLOW_SPD_ADD
CDC_FAN_MIN_SPD_ADD
BDC_FAN_MID_SPD_ADD
ADC_FAN_HI_SPD_ADD
21℃
19℃
18℃
16℃
15℃
13℃
12℃
10℃
7.4.4 Electronic Expansion Valve (EXV)
Control
1.EXV will be fully closed when turning on the
power. Then EXV will be standby with 350P open
and will open to target angle after compressor
starts.
2.EXV will close with -160P when compressor
stops. Then EXV will be standby with 350P open
and will open to target angle after compressor
starts.
3.The action priority of the EXVs is A-B-C-D.
4.Compressor and outdoor fan start operation
only after EXV is initialized.
7.4.4.1 Cooling mode
The initial open angle of EXV is 250P, adjustment
range is 100-350p. When the unit start to work for
3 minutes, the outdoor will receive indoor units( of
capacity demand) T2B information and calculate
the average of them. After comparing each
indoor’s T2B with the average, the outdoor gives
the following modification commands:
If the T2B＞average, the relevant valve needs
more 16p open;
If the T2B= average, the relevant valve’s open
range remains;
If the T2B＜average, the relevant valve needs
more 16p close.
This modification will be carried out every 2
minutes.
7.4.4.2 Heating mode
The initial open angle of EXV is 250P, adjustment
range is 100-350p.. When the unit start to work
for 3minutes, the outdoor will receive indoor
units( of capacity demand) T2 information and
calculate the average of them. After comparing
each indoor’s T2 with the average, the outdoor
gives the following modification commands:
If the T2＞average+2, the relevant valve needs
more 16p close;
If average+2≥the T2≥ average-2, the relevant
valve’s open range remains;
If the T2＜average-2, the relevant valve needs
more 16p open.
This modification will be carry out every 2 minutes.
7.4.5 Four-way valve control
In heating mode, four-way valve is opened. In
defrosting, four-way valve operates in according
to defrosting action. In other modes, four-way
valve is closed. When the heating mode to other
modes, the four-way valve is off after compressor
is off for 2 minutes. Failure or protection (not
including discharge temperature protection, high
and low pressure protection), four-way valve
immediately shuts down.

8. Wiring Diagrams
8.1 Wiring diagram of 1 drive 2 outdoor
M2OC-18HFN1-M, M2OD-18HFN1-M

PCB board of M2OC-18HFN1-M, M2OD-18HFN1-M