Midea MCH2U-18PHH2 User manual

1
MULTI OUTDOOR UNITS
SERVICE MANUAL
Multi zone
CONDENSING UNITS
Revision C: ODMI-E-1606
Model Numbers:
MCH2U-18PHH2 MCH3U-27PHH2 MCH4U-36PHH2
MCH5U-48PHH2
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. Indoor Unit Combination
2. Suggested Indoor Unit Model Numbers
3. Dimension Of Outdoor Unit
4. Refrigerant Cycle Diagram
5. Installation Details
6. Electronic Function
7. Wiring Diagrams
8. Trouble Shooting
9. Disassembly Instructions

2
CONTENTS
1. Indoor Unit Combination .................................................................................................................................... 4
2. Dimension Of Outdoor Unit ................................................................................................................................ 6
3. Refrigerant Cycle Diagram .................................................................................................................................. 7
4. Installation Details ............................................................................................................................................ 10
4.1 Wrench torque sheet for installation .......................................................................................................... 10
4.2 Connecting the cables ................................................................................................................................. 10
4.3 Pipe length and the elevation ..................................................................................................................... 10
4.4 First-Time Installation ................................................................................................................................. 11
4.5 Adding Refrigerant after Long-Term System Operation ............................................................................... 12
4.6 Procedure when servicing the indoor unit refrigeration circuit. ................................................................... 12
4.7 Evacuation after servicing the outdoor unit refrigeration circuit ................................................................. 14
6. Electronic Function ........................................................................................................................................... 15
6.1 Abbreviation ............................................................................................................................................... 15
6.2 Electric Control Working Environment. ....................................................................................................... 15
6.3 Main Protection .......................................................................................................................................... 15
6.4 Control and Functions ................................................................................................................................. 17
7. Wiring Diagrams ............................................................................................................................................... 23
8. Troubleshooting ............................................................................................................................................... 33
8.1Safety .......................................................................................................................................................... 33
8.2 Indoor Unit Error Display ............................................................................................................................. 34
8.3 Outdoor Unit Display .................................................................................................................................. 37
8.4 Diagnosis and Solution ................................................................................................................................ 42
8.5 Trouble Criterion Of Main Parts. ................................................................................................................. 91
9. Disassembly Instructions ................................................................................................................................ 103
 MCH2U-18PHH2 (WCA30 metal plate) .............................................................................................. 103
 MCH3U-27PHH2 (WD30 metal plate) ................................................................................................. 110

3
 MCH4U-36PHH2 (WD30 metal plate) ................................................................................................. 118
 MCH5U-48PHH2 (WE30 metal plate) ................................................................................................. 125

4
1. Indoor Unit Combination
Multi DC
Outdoor
Unit
Nominal
capacity
Suggested
Combination Limit
1drive 2 5.2kW
12
None
9+9
9+12
12+12
Multi DC
Outdoor
Unit
Nominal
capacity
Suggested
Combination Limit
1 drive 5 14kW
18+18
None
18+24
24+24
9+9+18
9+9+24
9+12+12
9+12+18
9+12+24
9+18+18
9+18+24
9+24+24
12+12+12
12+12+18
12+12+24
12+18+18
12+18+24
12+24+24
18+18+18
18+18+24
9+9+9+9
9+9+9+12
9+9+9+18
9+9+9+24
9+9+12+12
Multi DC
Outdoor
Unit
Nominal
capacity
Suggested
Combination Limit
1drive 3 7.8kW
9+9
None
9+12
9+18
12+12
12+18
18+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 10.5kW
9+18
None
12+12
12+18
18+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
9+9+9+9
9+9+9+12
9+9+9+18
9+9+12+12
9+9+12+18
9+12+12+12
12+12+12+12

5
9+9+12+18
9+9+12+24
9+9+18+18
9+9+18+24
9+12+12+12
9+12+12+18
9+12+12+24
9+12+18+18
9+18+18+18
12+12+12+12
12+12+12+18
12+12+12+24
12+12+18+18
9+9+9+9+9
9+9+9+9+12
9+9+9+9+18
9+9+9+9+24
9+9+9+12+12
9+9+9+12+18
9+9+9+18+18
9+9+12+12+12
9+9+12+12+18
9+12+12+12+12
9+12+12+12+18
12+12+12+12+12

6
2. Dimension Of Outdoor Unit
Model Unit： W D H W1 A B
MCH2U-18PHH2
mm 845 363 702 923 540 350
inch
33.3
14.3
27.6
36.0
21.3
13.8
MCH3U-27PHH2
mm 946 410 810 1034 673 403
inch
37.2
16.5
31.9
40.6
26.5
15.9
MCH4U-36PHH2
mm 946 410 810 1034 673 403
inch
37.2
16.5
31.9
40.6
26.5
15.9
MCH5U-48PHH2
mm 952 415 1333 1060 634 404
inch
37.5
16.3
52.5
41.7
25.0
15.9
A
B
D

7
3. Refrigerant Cycle Diagram
3.1 Refrigeration circuit drawing of inverter 1 drive 2 type
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
3.2 Refrigeration circuit drawing of inverter 1 drive 3 type
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

8
3.3 Refrigeration circuit drawing of inverter 1 drive 4 type
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
3.4 Refrigeration circuit drawing of inverter 1 drive 5 type

9
LIQUID VALVE A
GAS VALVE A
HEAT
EXCHANGE
(EVAPORATOR)
HEAT
EXCHANGE
(CONDENSER)
COOLING
HEATING
T2 Evaporator
temp. sensor
T1 Room
temp. sensor
T3
Condenser
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
EXV E CAPILIARY E
LIQUID VALVE E
GAS VALVE E
Compressor
4-WAY VALVE
T5 Discharge
temp. sensor
Accumulator High pressure
switch
Low pressure
switch
T2B-A Evaporator
temp. sensor outlet
T2B-B
T2B-C
T2B-D
T2B-E

10
4. Installation Details
4.1 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)
4.2 Connecting the cables
The power cord connection should be
selected according to the following
specifications sheet.
Unit AWG
1 drive 2 type (18K outdoor unit)
14
1 drive 3 type (27K outdoor unit).
14
1 drive 4 type (36K outdoor unit)
12
1 drive 5 type (48K outdoor unit)
10
For indoor unit and outdoor unit
connection line, 16AWG is ok for all.
4.3 Pipe length and the elevation
Maximum piping length and height
difference
1 drive
2
1 drive
3
1 drive
4
1 drive
5
Max. length
for all rooms
(m)
40
(131ft)
60
(197ft)
80
(262ft)
80
(262ft)
Max. length
for one IU
(m)
25
(82ft)
30
(98ft)
35
(115ft)
35
(115ft)
Max. height
difference
between IU
and OU (m)
15
(49.2ft)
15
(49.2ft)
15
(49.2ft)
15
(49.2ft)
Max. height
difference
between IUs
(m)
10
(33ft)
10
(33ft)
10
(33ft)
10
(33ft)
Additional refrigerant charge
1 drive
2
1 drive
3
1 drive
4
1 drive
5
Pre-charge
pipe length
(m)
15
(49.2ft)
22.5
(73.8ft)
30
(98.4ft)
37.5
(123ft)
Additio
nal
refriger
ant
charge
g
15 x
(length
for all
rooms -
15)
15 x
(length
for all
rooms
– 22.5)
15 x
(length
for all
rooms -
30)
15 x
(length
for all
rooms
– 37.5)
oz
0.161
x(lengt
h for all
rooms
– 49.2)
(0.161
x(lengt
h for all
rooms
– 73.8)
0.161x(
length
for all
rooms
– 98.4)
.0.161x
(length
for all
rooms
–123)
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 the outdoor unit
connector (18K indoor unit) an additional
adapter is required.
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)
24K Liquid
9.52 (3/8)
Liquid
9.52 (3/8)
Gas 15.9(5/8) Gas 15.9(5/8)
Outdoor unit union diameter (mm/inch)
1 drive 2
Liquid
6.35(1/4)
*2
Gas 9.52(3/8)
*2
1 drive 3
Liquid
6.35(1/4)
*3
Gas 9.52(3/8)
*3
1 drive 4
Liquid
6.35(1/4)
*4
Gas 9.52(3/8)
*3
12.7(1/2)
*
1
1 drive 5
Liquid
6.35(1/4)
*5
Gas 9.52(3/8)
*3
12.7(1/2)
*
2

11
4.4 First-Time Installation
Air and moisture in the refrigerant system
cause the following problems:
● Increases in system pressure
● Increases in operating current
● Decreases in cooling and heating
efficiency
● Blocks in capillary tubing caused by
moisture in the refrigerant circuit freezing
● Corrosion of parts in the refrigerant
system caused by water
The indoor units and the pipes between
indoor and outdoor units must be tested for
leakages and evacuated to remove gas and
moisture from the system.
Gas leak check with soap water:
Apply soap water or a liquid neutral
detergent on the connections with a soft
brush to check for leakage in the pipe
connecting points. If bubbles emerge, the
pipes are leaking.
1. Air Purging Using the Vacuum Pump
1. Completely tighten the flare nuts on the
indoor and outdoor units. Confirm that
both the2-way and 3-way valves are set
to the closed position.
2. Connect the charge hose with the push
pin of the Handle Lo to the 3-way valve
gas service port.
3. Connect the charge hose of the Handle
Hi to the vacuum pump.
4. Fully open the Handle Lo of the manifold
valve.
5. Turn on the vacuum pump to begin
evacuation.
6. Conduct a 30-minute evacuation. Check
whether the compound meter indicates -
0.1Mpa(14.5Psi). If the meter does not
indicate -0.1Mpa(14.5Psi) after 30
minutes has elapsed, continue
evacuation for 20 more minutes. If the
pressure does not reach -
0.1Mpa(14.5Psi) after 50 minutes has
elapsed, check if there are any leaks.
Fully close the Handle Lo valve of the
manifold valve and turn off the vacuum
pump. After 5 minutes, confirm that the
gauge needle is not moving.
7. Turn the flare nut on the 3-way valve45°
counterclockwise for 6-7 seconds. Once
gas begins to come out, tighten the flare
nut. Make sure the pressure display on
the pressure indicator is higher than
atmospheric pressure. Then remove the
charge hose from the 3-way valve.
8. Fully open the 2-wayand 3-way valves
and securely tighten the cap on the 3-
way valve.
2. Adding refrigerant if the pipe length
exceeds chargeless pipe length
Procedure:

12
1)
Connect the charge hose to the charging
cylinder and open the 2-way and 3-way
valves.
With the charge hose you disconnected
from the vacuum pump, connect it to the
valve at the bottom of the cylinder.
If the refrigerant is R410A, place the
cylinder bottom-up to ensure liquid charging
is possible.
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
(be careful of the liquid refrigerant).
3) Place the charging cylinder onto the
electronic scale and record the weight.
4) Turn on the air conditioner in cooling
mode.
5) Open the valves (Low side) on the charge
set. 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 before disconnecting the hose.
7). Mount the valve stem caps and the service
port
Use a torque wrench to tighten the service
port cap to a torque of 18N.m(13.27 ft·lbs).
Be sure to check for gas leaks.
4.5 Adding Refrigerant after Long-
Term System Operation
Procedure
1)
Connect the charge hose to the 3-way
service port and open the 2-way and 3-way
valve.
Connect the charge hose to the valve at the
bottom of the cylinder. If the refrigerant is
R410A, place 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) Place the charging cylinder onto the
electronic scale and record the weight.
4) Turn on the air conditioner in 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(13.27 ft·lbs).
Be sure to check for gas leaks.
4.6 Procedure when servicing the
indoor unit refrigeration circuit.
1. Collecting the refrigerant into the
outdoor unit

13
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.
6). Set the 3-way valve to the closed position
immediately
Do this quickly so that the gauge ends up
indicating 0.3 to 0.5Mpa.
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. If the meter does not
indicate -0.1Mpa after pumping 30
minutes, it should be pumped 20 minutes
more. If the pressure can’t achieve -
0.1Mpa 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

14
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.
4.7 Evacuation after servicing the
outdoor unit refrigeration circuit
1. Evacuation of the complete
refrigeration circuit, Indoor and outdoor
unit.
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 (500 Microns / 29.9 in,hg).
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 (13.27
ft·lbs).
Always leak check after servicing the

15
refrigerant system.
For MCH3U-27PHH2/MCH4U-
36PHH2/MCH5U-48PHH2
There are one low-pressure centralized valve
and one high-pressure centralized valve, it will
be more time saving when vacuum and
recycle refrigerant. But refer to the previous
instruction when vacuum and recycle
refrigerant.
6. Electronic Function
6.1 Abbreviation
T1: Indoor ambient temperature
T2: Middle indoor heat exchanger coil
temperature
T2B: Indoor heat exchanger exhaust coil
temperature (located on the outdoor unit)
T3: Outdoor heat exchanger pipe
temperature
T4: Outdoor ambient temperature
T5: Compressor discharge temperature
6.2 Electric Control Working
Environment.
6.2.1 Input voltage: 230V.
6.2.2 Input power frequency: 60Hz.
6.2.3 Indoor fan standard working amp.: <1A
6.2.4 Outdoor fan standard working amp.:
<1.5A.
6.2.5 Four-way valve standard amp.: <1A.
6.3 Main Protection
6.3.1 Compressor Restart Delay
---- The compressor takes 1 minute to start
up the first time. Further restarts take 3
minutes.
6.3.2 Temperature Protection of
Compressor Discharge.
When the discharge temperature of the
compressor rises, the running frequency is
limited according to the following rules:
----If 105℃ (221 ℉)≦T5<110℃ (230 ℉),
maintain the current frequency.

16
----If the temperature increase and T5≧110℃
(230 ℉), decrease the frequency to a lower
level every 2 minutes till to F1.
---If T5≧115℃ (239 ℉) for 10 seconds, the
compressor stops and then restart untill
T5<90℃ (194 ℉).
6.3.3 Fan Speed Malfunction
---- If outdoor fan speed is lower than
100RPM or higher than 2400RPM for 60
seconds or more, the unit stops and LED
displays
E8
failure code.
6.3.4 Inverter Module Protection.
---- The inverter protection module ensures
that faults related to current, voltage, or
temperature does not damage the inverter.
If these protections are triggered, the A/C
unit stops and the LED displays the failure
code.
The unit restarts 3 minutes after the
protection mechanism has turned off.
6.3.5 Low Voltage Protection
V O LT AG E
N o lim it
V O L T _ LT M _ F R E Q 1 _ AD D
V O L T _ L T M _ F R E Q 2 _ A D D
Note: If low voltage protection triggers and
voltage is not restored to normal within 3
minutes, the protection remains active
even after a machine restart.
6.3.6 Compressor Current Limit
Protection
The temperature interval for the current limit
is the same as the range of the T4
frequency limit.
Cooling mode:
CoolReturnI The difference between
current limit
and shutdown current
CoolT4Zone5I
Cooling T4≥50℃ current
limit value
CoolT4Zone4I
Cooling 49＞T4≥45℃
current limit value
CoolT4Zone3I
Cooling 44＞T4≥41℃
current limit value
CoolT4Zone2I
Cooling 40﹥T4≥33℃
current limit value
CoolT4Zone1I
Cooling 32＞T4℃current
limit value
CoolStopI Cooling stop protection
current value
Heating mode:
℃ CoolT4Zone5I
50
49
45 CoolT4Zone4I
44
41
40 CoolT4Zone3I
33
32
CoolT4Zone2I

17
℃
15
14 HeatT4Zone4I
10
9 HeatT4Zone3I
6
5 HeatT4Zone2I
HeatT4Zone1I
HeatReturnI The difference between
current limit
and shutdown current
HeatT4Zone4I
Heating T4≥15℃current
limit value
HeatT4Zone3I
Heating 14＞T4≥10℃
current limit value
HeatT4Zone2I
Heating 9＞T4≥6℃
current limit value
HeatT4Zone1I
Heating 5＞T4 current limit
value
HeatStopI Heating stop protection
current value
6.3.7 Indoor / Outdoor Units
Communication Protection
If the indoor units do not receive the
feedback signal from the outdoor units for 2
consecutive minutes, the unit stops. The
unit displays the failure code.
6.3.8 High Condenser Coil Temp.
Protection
6.3.9 Outdoor Unit Anti-Freezing
Protection
When T2<4℃ for 250seconds or T2<0℃,
the indoor unit capacity demand is zero and
resumes normal operation when T2>8℃
and the protection time is no less than 3
minutes.
6.3.10 Oil Return
Rules for Operation
1. If the compressor frequency continues to
be lower than the frequency set for setting
time, the unit raises the frequency to the
frequency set for setting time and then
resumes with the former frequency.
2. The EXV continues at 300p while indoor
units maintain their operation.
If the outdoor ambient temperature is higher
than the set frequency during oil return, the
unit stops the oil return process.
6.3.11 Low Outdoor Ambient
Temperature Protection
When the compressor is off and T4 is lower
than -35℃ for 10 seconds, the unit stops
and displays “LP.”
When the compressor is on and T4 remains
lower than -40℃ for 10 seconds, the unit
stops and displays “LP.”
When T4 is no lower than -32℃ for 10
seconds, the unit exits protection.
6.4 Control and Functions
6.4.1 Capacity Request Calculation
Cooling Mode:
T3
Resume
Off
Decrease
Hold

18
T1 Ts
3
1
1
e
c
a4
2
0
2
3
0
1
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 24K
HP 1.0 1.2 1.5 2.5
Note: The final result is an integer.
Use the following table and final capacity
request to confirm the operating
frequency.
Frequency
(Hz) 0
CO
OL_
F1
CO
OL_
F2
…
…
COO
L_F2
4
CO
OL_
F25
Amendatory
capacity
demand.
0
1 2 …
…
24 25
The maximum running frequency is
adjusted according to the outdoor ambient
temperature
℃
55
54 Fmax= T4FREMAXC0
51.5
50.5 Fmax= T4FREMAXC1
45.5
44.5 Fmax= T4FREMAXC2
39
38 Fmax= T4FREMAXC3
33
32 Fmax= T4FREMAXC4
30
29 Fmax= T4FREMAXC5
22
20 Fmax= T4FREMAXC6
10
8 Fmax= T4FREMAXC7
0
-2 Fmax= T4FREMAXC8
-10
-12 Fmax= T4FREMAXC9
Fmax= T4FREMAXC10
Heating Mode
T1 Ts
4
0
a
3
1
-1
3
1
2
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 24K
HP 1.0 1.2 1.5 2.5
Note: The final result is an integer.

19
Then modify it according to a T2 average
(correction):
Note:Average value of T2：Sum T2 value of
all indoor units)/ (indoor units number
℃
T2 average
Decrease frequency
47
Keep frequency
40 Increase frequency
Use the following table and final capacity
request to confirm the operating
frequency.
Frequency
(Hz) 0
HEA
T_F
1
HEA
T
_F2
…
HEA
T
_F24
HEA
T
_F2
5
Amendatory
capacity
demand.
0
1 2 …
24 25
The maximum running frequency is
adjusted according to the outdoor ambient
temperature
℃
34
33 Standby
28
27 Fmax=T4FREHEATMAX1
25
24 Fmax=T4FREHEATMAX2
22
21 Fmax=T4FREHEATMAX3
19
18 Fmax=T4FREHEATMAX4
17
16 Fmax=T4FREHEATMAX5
15
14 Fmax=T4FREHEATMAX6
12
11 Fmax=T4FREHEATMAX7
6
5 Fmax=T4FREHEATMAX8
1
0 Fmax=T4FREHEATMAX9
-3
-4 Fmax=F21
-7
-8 Fmax=F22
-11
-12 Fmax=F23
-15
-16 Fmax=F24
Fmax=F25
6.4.2 Defrosting Control
Conditions for Defrosting:
After the compressor starts and enters
normal operation, mark the minimum value
of T3 from the 10th to 15th minute as T30.
If any one of the following conditions is
satisfied, the unit enters defrosting mode:
1) If the compressor’s cumulative running
time reaches 29 minutes and T3< TCDI1
and T3＋T30SUBT3ONE≦T30.

20
2) If the compressor cumulative running
time reaches 35 minutes and T3< TCDI2
and T3＋T30SUBT3TWO≦T30.
3) If the compressor cumulative running
time reaches 40 minutes and T3< -24C for 3
minutes.
4) If the compressor cumulative running
time reaches 120 minutes and T3<-15℃.
Defrost Stop Conditions
If any one of the following conditions is
satisfied, defrosting ends and the unit
returns to normal heating mode:
----T3 rises above than TCDE1℃.
----T3 remains at TCDE2℃ or above for 80
seconds.
----The machine runs for 10 consecutive
minutes in defrosting mode.
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.
① T3 > TempQuitDefrost_ADD ℃;.
② The defrosting time achieves 10min.
③ Turn to other modes or off.
6.4.3 Outdoor Fan Control
6.4.3.1 Cooling Mode
Under normal operating conditions, the
system chooses the running fan speed
according to the ambient temperature:
O
utdoor temperature
℃
45
43 Supper high fan speed
28
26 High fan speed
25
23 Middle fan speed
22
20 Low fan speed
19
17 Supper low fan speed
10
9 Breeze fan speed
0
-1 F fan speed
-5
-6 G fan speed
-10
-11 H fan speed
I fan speed
When low ambient cooling is in effect::
Outdoor fan speed control logic (low
ambient cooling)
When T4 <15 ℃ (59 ℉) and T3 < 30 ℃ (86
℉), the unit enters into low ambient cooling
mode. The outdoor fan chooses a speed
according to T3.
When T3≥38 ℃ (100.4 ℉) or when T4≥20 ℃
(68 ℉), the outdoor fan chooses a speed
according to T4 again.