LG Multi V User manual

Air Conditioner
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Copyright © 2020 LG Electronics Inc. All rights reserved. Only training and service purposes.
SERVICE MANUAL (R410A)
CAUTION
Before Servicing the unit, read the safety precautions in General SVC manual.
Only for authorized service personnel.
CONFIDENTIAL

- 2 -
Copyright © 2020 LG Electronics Inc.
All rights reserved. Only training and service purposes.
Air Conditioner Service Manual
TABLE OF CONTENTS
Safety Precautions .....................................................................................................3
Part 1 General Information ........................................................................................8
Model Names ...............................................................................................................................9
External Appearance..................................................................................................................11
Nomenclature .............................................................................................................................13
Part 2 Outdoor Units ................................................................................................15
Part 3 HR Units .........................................................................................................36
Part 4 PCB Setting and Test Run ...........................................................................54
Part 5 Trouble shooting guide................................................................................ 87

Safety Precautions
- 3 -
Copyright © 2020 LG Electronics Inc.
All rights reserved. Only training and service purposes.
Safety Precautions
To prevent injury to the user or other people and property damage, the following instructions must
be followed.
nIncorrect operation due to ignoring instruction will cause harm or damage. The seriousness is
classified by the following indications.
nMeanings of symbols used in this manual are as shown below.
WARNING
CAUTION
This symbol indicates the possibility of death or serious injury.
This symbol indicates the possibility of injury or damage to properties only.
Be sure not to do.
Be sure to follow the instruction.
WARNING
nInstallation
Have all electric work done by a licensed
electrician according to "Electric Facility
Engineering Standard" and "Interior Wire
Regulations" and the instructions given in
this manual and always use a special circuit.
• If the power source capacity is inadequate or
electric work is performed improperly, electric
shock or fire may result.
Ask the dealer or an authorized technician to
install the air conditioner.
• Improper installation by the user may result in
water leakage, electric shock, or fire.
Always ground the product.
• There is risk of fire or electric shock.
Always intstall a dedicated circuit and breaker.
• Improper wiring or installation may cause fire or
electric shock.
For re-installation of the installed product,
always contact a dealer or an Authorized
Service Center.
• There is risk of fire, electric shock, explosion, or
injury.
Do not install, remove, or re-install the unit
by yourself (customer).
• There is risk of fire, electric shock, explosion, or
injury.

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Copyright © 2020 LG Electronics Inc.
All rights reserved. Only training and service purposes.
Safety Precautions
Do not store or use flammable gas or
combustibles near the air conditioner.
• There is risk of fire or failure of product.
Use the correctly rated breaker or fuse.
• There is risk of fire or electric shock.
Prepare for strong wind or earthquake and
install the unit at the specified place.
• Improper installation may cause the unit to top-
ple and result in injury.
Do not install the product on a defective
installation stand.
• It may cause injury, accident, or damage to the
product.
When installing and moving the air condition-
er to another site, do not charge it with a
different refrigerant from the refrigerant
specified on the unit.
• If a different refrigerant or air is mixed with the
original refrigerant, the refrigerant cycle may
malfunction and the unit may be damaged.
Do not reconstruct to change the settings of
the protection devices.
• If the pressure switch, thermal switch, or other
protection device is shorted and operated
forcibly, or parts other than those specified by
LGE are used, fire or explosion may result.
Ventilate before operating air conditioner
when gas leaked out.
• It may cause explosion, fire, and burn.
Securely install the cover of control box and
the panel.
• If the cover and panel are not installed securely,
dust or water may enter the outdoor unit and fire
or electric shock may result.
If the air conditioner is installed in a small
room, measures must be taken to prevent the
refrigerant concentration from exceeding the
safety limit when the refrigerant leaks.
• Consult the dealer regarding the appropriate
measures to prevent the safety limit from being
exceeded. Should the refrigerant leak and cause
the safety limit to be exceeded, harzards due to
lack of oxygen in the
room could result
Use a vacuum pump or inert(nitrogen) gas when
doing leakage test or air purge. Do not compress
air or Oxygen and do not use flammable gas es.
Otherwise, it may cause fire or explosion.
• There is the risk of death, injury, fire or explo-
sion.

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Copyright © 2020 LG Electronics Inc.
All rights reserved. Only training and service purposes.
nOperation
Safety Precautions
Do not damage or use an unspecified power cable.
• There is risk of fire, electric shock, explosion, or
injury.
Use a dedicated power cable for this appli-
ance.
• There is risk of fire or electrical shock.
Be cautious that water could not enter the product.
• There is risk of fire, electric shock, or product
damage.
Do not touch the power switch with wet hands.
• There is risk of fire, electric shock, explosion, or
injury.
When the product is soaked (flooded or
submerged), contact an Authorized Service
Center.
• There is risk of fire or electric shock.
Be cautious not to touch the sharp edges
when installing.
• It may cause injury.
Take care to ensure that nobody could step
on or fall onto the outdoor unit.
• This could result in personal injury and product
damage.
Do not open the inlet grille of the product
during operation. (Do not touch the electro-
static filter, if the unit is so equipped.)
• There is risk of physical injury, electric shock, or
product failure.
CAUTION
nInstallation
Always check for gas (refrigerant) leakage
after installation or repair of product.
• Low refrigerant levels may cause failure of
product.
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.
Keep level even when installing the product.
• To avoid vibration or water leakage.
Do not install the unit where combustible gas
may leak.
• If the gas leaks and
accumulates around the
unit, an explosion may
result.

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Copyright © 2020 LG Electronics Inc.
All rights reserved. Only training and service purposes.
Safety Precautions
Use power cables of sufficient current
carrying capacity and rating.
• Cables that are too small may leak, generate
heat, and cause a fire.
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
refrigeration system.
• There is risk of damage or loss of property.
Keep the unit away from children. The heat
exchanger is very sharp.
• It can cause the injury, such as cutting the finger.
Also the damaged fin may result in degradation
of capacity.
When installting the unit in a hospital, com-
munication station, or similar place, provide
sufficient protection against noise.
•
The inverter equipment, private power generator,
high-frequency medical equipment, or radio com-
munication equipment may cause the air condition-
er to operate erroneously, or fail to operate. On the
other hand, the air conditioner may affect such
equipment by creating noise that disturbs medical
treatment or image broadcasting.
Do not install the product where it is 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.
nOperation
Do not use the air conditioner in special
environments.
• Oil, steam, sulfuric smoke, etc. can significantly
reduce the performance of the air conditioner or
damage its parts.
Do not block the inlet or outlet.
• It may cause failure of appliance or accident.
Make the connections securely so that the
outside force of the cable may not be applied
to the terminals.
• Inadequate connection and fastening may gen-
erate heat and cause a fire.
Be sure the installation area does not deteri-
orate with age.
• If the base collapses, the air conditioner could
fall with it, causing property damage, product
failure, or personal injury.

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Copyright © 2020 LG Electronics Inc.
All rights reserved. Only training and service purposes.
Safety Precautions
Install and insulate the drain hose to ensure
that water is drained away properly based on
the installation manual.
• A bad connection may cause water leakage.
Be very careful about product transportation.
• Only one person should not carry the product if it weighs
more than 20 kg (44.1 lbs).
• Some products use PP bands for packaging. Do not use
any PP bands for a means of transportation. It is dangerous.
• Do not touch the heat exchanger fins. Doing so may cut
your fingers.
• When transporting the outdoor unit, suspending it at the
specified positions on the unit base. Also support the out-
door unit at four points so that it cannot slip sideways.
Safely dispose of the packing materials.
•
Packing materials, such as nails and other metal or
wooden parts, may cause stabs or other injuries.
• Tear apart and throw away plastic packaging bags
so that children may not play with them. If children
play with a plastic bag which was not torn apart,
they face the risk of suffocation.
Turn on the power at least 6 hours before
starting operation.
• Starting operation immediately after turning on
the main power switch can result in severe
damage to internal parts. Keep the power switch
turned on during the operational season.
Do not touch any of the refrigerant piping
during and after operation.
• It can cause a burn or frostbite.
Do not operate the air conditioner with the
panels or guards removed.
• Rotating, hot, or high-voltage
parts can cause injuries.
Do not directly turn off the main power
switch after stopping operation.
• Wait at least 5 minutes before turning off the
main power switch. Otherwise it may result in
water leakage or other problems.
Auto-addressing should be done in condition of
connecting the power of all indoor and outdoour
units. Auto-addressing should also be done in
case of changing the indoor unit PCB.
Use a firm stool or ladder when cleaning or
maintaining the air conditioner.
• Be careful and avoid personal injury.
Do not insert hands or other objects through
the air inlet or outlet while the air conditioner
is powered on.
• There are sharp and moving parts that could
cause personal injury.

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Copyright © 2020 LG Electronics Inc.
All rights reserved. Only training and service purposes.
Part 1
General Information
1. Model Names ..................................................................9
1.1 Indoor Unit ...............................................................9
1.2 Outdoor Unit ............................................................9
1.3 HR Unit ...................................................................10
2. External Appearance .....................................................11
2.1 Indoor Unit .............................................................11
2.2 Outdoor Unit ..........................................................12
3. Nomenclature.................................................................13
3.1 Indoor Unit .............................................................13
3.2 Outdoor Unit ..........................................................13
3.3 HR Unit ...................................................................14

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Copyright © 2020 LG Electronics Inc.
All rights reserved. Only training and service purposes.
1. Model Names
1.1 Indoor Unit
Model Names
1.2 Outdoor Unit
Power Supply 3TON 4TON
1 Ø, 208/230 V, 60 Hz ARUM036GSS5 ARUM048GSS5
h*Wall Mounted - L : Basic, R : Mirror
*Ceiling Cassette - A : Basic, C : Plasma
*Ceiling Concealed Duct - A : Basic, Z : FAU
Category Chassis
Name
Capacity[Btu/h(kW)]
5.5 (1.6) 7.2 (2.2) 9.6 (2.8) 12.3 (3.6) 15.4 (4.5) 19.1 (5.6) 24.2 (7.1) 28.0 (8.2) 30.0 (8.8) 36.2 (10.6)42.0 (12.3)48.1 (14.1)54.0 (15.8)76.4 (22.4)96.5 (28.0)
Wall Mounted
SB ARNU053
SB*4
ARNU073
SB*4
ARNU093
SB*4
ARNU123
SB*4
ARNU153
SB*4
SC ARNU183
SC*4
ARNU243
SC*4
SV ARNU303
SVA4
ARNU363
SVA4
ART
COOL SF ARNU093
SFA4
ARNU123
SFA4
Ceiling
Cassette
1 Way
TU ARNU073
TUC4
ARNU093
TUC4
ARNU123
TUC4
TT ARNU183
TTC4
ARNU243
TTC4
2 Way TL ARNU183
TLC4
ARNU243
TLC4
4 Way
TR ARNU053
TRC4
ARNU073
TRC4
ARNU093
TRC4
ARNU123
TRC4
TQ ARNU153
TQC4
ARNU183
TQC4
TP ARNU243
TPC4
ARNU283
TPC4
TN ARNU073
TNA4
ARNU093
TNA4
ARNU123
TNA4
ARNU153
TNA4
ARNU183
TNA4
ARNU243
TNA4
ARNU363
TNA4
TM ARNU243
TMA4
ARNU283
TMA4
ARNU363
TMA4
ARNU423
TMA4
ARNU483
TMA4
Ceiling
Concealed
Duct
High
Static
BH ARNU073
BHA4
ARNU093
BHA4
ARNU123
BHA4
ARNU153
BHA4
ARNU183
BHA4
ARNU243
BHA4
BG ARNU073
BGA4
ARNU093
BGA4
ARNU123
BGA4
ARNU153
BGA4
ARNU183
BGA4
ARNU243
BGA4
ARNU283
BGA4
ARNU363
BGA4
ARNU423
BGA4
BR ARNU283
BRA4
ARNU363
BRA4
ARNU423
BRA4
ARNU483
BR*4
ARNU543
BRA4
B8 ARNU363
B8A4
ARNU423
B8A4
ARNU483
B8A4
ARNU763
B8*4
ARNU963
B8*4
Low
Static
L1 ARNU073
L1G4
ARNU093
L1G4
L2 ARNU123
L2G4
ARNU153
L2G4
ARNU183
L2G4
L3 ARNU243
L3G4
Built
In
B3 ARNU073
B3G4
ARNU093
B3G4
ARNU123
B3G4
ARNU153
B3G4
B4 ARNU183
B4G4
ARNU243
B4G4
Ceiling & Floor VE ARNU093
VEA2
ARNU123
VEA2
Ceiling Suspended VJ ARNU183
VJA2
ARNU243
VJA2
Floor
Standing
With
Case
CE ARNU073
CEA4
ARNU093
CEA4
ARNU123
CEA4
ARNU153
CEA4
CF ARNU183
CFA4
ARNU243
CFA4
Without
Case
CE ARNU073
CEU4
ARNU093
CEU4
ARNU123
CEU4
ARNU153
CEU4
CF ARNU183
CFU4
ARNU243
CFU4
Vertical AHU
NJ ARNU123
NJA4
ARNU183
NJA4
ARNU243
NJA4
ARNU303
NJA4
ARNU363
NJA4
NK ARNU423
NKA4
ARNU483
NKA4
ARNU543
NKA4

Model Names
- 10 -
Copyright © 2020 LG Electronics Inc.
All rights reserved. Only training and service purposes.
Power Supply 2 branches 3 branches 4 branches
1Ø, 220-240 V, 50 Hz / 1Ø, 220 V, 60 Hz PRHR023 PRHR033 PRHR043
1Ø, 208/230 V, 60 Hz PRHR023A PRHR033A PRHR043A
Power Supply 6 branches 8 branches
1Ø, 220-240 V, 50 Hz / 1Ø, 220 V, 60 Hz PRHR063 PRHR083
1Ø, 208/230 V, 60 Hz PRHR063A PRHR083A
1.3 HR Unit
Power Supply 2 branches 3 branches 4 branches
1Ø, 208/230 V, 60 Hz PRHR022A PRHR032A PRHR042A
2 Series
3 Series

External Appearance
- 11 -
Copyright © 2020 LG Electronics Inc.
All rights reserved. Only training and service purposes.
2. External Appearance
2.1 Indoor Unit
Wall Mounted
ART COOL
Ceiling Cassette- 1Way
Ceiling Cassette- 4Way
Ceiling & Floor
Ceiling Suspended
ARNU073TUD4
ARNU093TUD4
ARNU123TUD4
ARNU183TTD4
ARNU243TTD4
Ceiling Cassette -2Way
ARNU183TSA4
ARNU243TSA4
ARNU053TRC4
ARNU073TRC4
ARNU093TRC4
ARNU123TRC4
ARNU153TQC4
ARNU053TRD4
ARNU073TRD4
ARNU093TRD4
ARNU123TRD4
ARNU183TQC4
ARNU153TQD4
ARNU183TQD4
ARNU243TPC4
ARNU283TPC4
ARNU073TNA4
ARNU093TNA4
ARNU123TNA4
ARNU153TNA4
ARNU183TNA4
ARNU243TNA4
ARNU363TNC4
ARNU243TMA4
ARNU283TMA4
ARNU363TMA4
ARNU423TMC4
ARNU483TMC4
Ceiling Concealed Duct - Low Static
ARNU073L1G4
ARNU093L1G4
ARNU123L2G4
ARNU153L2G4
ARNU183L2G4
ARNU243L3G4
ARNU053SJA4
ARNU053SJR4
ARNU073SJA4
ARNU073SJR4
ARNU093SJA4
ARNU093SJR4
ARNU123SJA4
ARNU123SJR4
ARNU153SJA4
ARNU153SJR4
ARNU183SKA4
ARNU183SKR4
ARNU243SKA4
ARNU243SKR4
ARNU303SVA4
ARNU363SVA4
ARNU093SFA4
ARNU123SFA4
ARNU093VEA2
ARNU123VEA2
URNU183VJA2
URNU243VJA2
Floor Standing
With case
ARNU073CEA4
ARNU093CEA4
ARNU123CEA4
ARNU153CEA4
ARNU183CFA4
ARNU243CFA4
Without case
ARNU073CEU4
ARNU093CEU4
ARNU123CEU4
ARNU153CEU4
ARNU183CFU4
ARNU243CFU4
Vertical AHU
ARNU123NJA4
ARNU183NJA4
ARNU243NJA4
ARNU303NJA4
ARNU363NJA4
ARNU423NKA4
ARNU483NKA4
ARNU543NKA4
Ceiling Concealed Duct - High Static
ARNU073BHA4
ARNU093BHA4
ARNU123BHA4
ARNU153BHA4
ARNU183BHA4
ARNU243BHA4
ARNU073BGA4
ARNU093BGA4
ARNU123BGA4
ARNU153BGA4
ARNU183BGA4
ARNU243BGA4
ARNU283BGA4
ARNU363BGA4
ARNU423BGA4
ARNU283BRA4
ARNU363BRA4
ARNU423BRA4
ARNU483BR*4
ARNU543BRA4
ARNU363B8A4
ARNU423B8A4
ARNU483B8*4
ARNU763B8*4
ARNU963B8*4
Ceiling Concealed Duct – Built-in
ARNU073B3G4
ARNU093B3G4
ARNU123B3G4
ARNU153B3G4
ARNU183B4G4
ARNU243B4G4
* A : Basic, R : Mirror
* A : Basic, Z : FAU
Ceiling Concealed Duct – Middle Static
ARNU073M1A4
ARNU093M1A4
ARNU123M1A4
ARNU153M1A4
ARNU183M1A4
ARNU243M1A4
ARNU073M2A4
ARNU093M2A4
ARNU123M2A4
ARNU153M2A4
ARNU183M2A4
ARNU243M2A4
ARNU283M2A4
ARNU363M2A4
ARNU423M2A4
ARNU283M3A4
ARNU363M3A4
ARNU423M3A4
ARNU483M3A4
ARNU543M3A4

- 12 -
Copyright © 2020 LG Electronics Inc.
All rights reserved. Only training and service purposes.
External Appearance
2.2 Outdoor Unit
CHASSIS Model Name External Appearance
U3 ARUM048GSS5
ARUM036GSS5

- 13 -
Copyright © 2020 LG Electronics Inc.
All rights reserved. Only training and service purposes.
Nomenclature
3. Nomenclature
3.1 Indoor Unit
3.2 Outdoor Unit
ARN U 307 ATR 4
Serial Number
Chassis Name
Electrical Ratings
1:1 Ø, 115 V, 60 Hz 2: 1 Ø, 220 V, 60 Hz 3:1 Ø, 208/230 V, 60 Hz
6:1 Ø, 220 ~ 240 V, 50 Hz 7: 1 Ø, 100 V, 50/60 Hz
Total Cooling Capacity in Btu/h
EX) 5,000 Btu/h →'05' 18,000 Btu/h → '18'
Combination of Inverter Type and
Cooling Only or Heat Pump
U: DC Inverter and H/P and C/O
System with
Indoor Unit using R410A
Combinations of functions
A:Basic function L:Neo Plasma(Wall Mounted)
C:Plasma(Ceiling Cassette) G: Low Static
ART COOL Type Panel Color
R:Mirror V:Silver B:Blue V: Silver E:Red G:Gold 1:Kiss X: DX-Coil
ARU M G S060 S5
Serial Number
S : Standard E : High Efficiency H : High Ambient
C : Cold Area R : Anti-Corosion N : Space Saving Model
Electrical Ratings
Air Discharge Type
S : Side Discharge T : Top Discharge
N : Top Discharge Standard H/P(380V)
L : Top Discharge special H/P
8 : 3 Ø, 380-415 V, 50 Hz 9: 3 Ø, 380 V, 60 Hz
A : 3 Ø, 220 V, 50 Hz L : 3 Ø, 380-415 V, 50 Hz / 3 Ø, 380 V, 50 Hz
G :1 Ø, 208/230 V, 60 Hz
Total Cooling Capacity in Horse Power(HP) unit
EX)60,000 Btu/h →‘060’
Combination of Inverter Type and
Cooling Only or Heat Pump
N : Inverter ans H/P V : Inverter and C/O B : Inverter and H/R
M : for both H/P and H/R
System with
Outdoor Unit using R410A
※ Heat recovery ventilator refer to the DX-Coil manual

- 14 -
Copyright © 2020 LG Electronics Inc.
All rights reserved. Only training and service purposes.
Serial Number
No. of Connected branches
02 : For 2 branches
03 : For 3 branches
04 : For 4 branches
06 : For 6 branches
08 : For 8 branches
Indicates that this is System
HR Unit using the R410A
PRHR 04 3 A
Nomenclature
3.3 HR Unit
※ These are model names of the basic function.

- 15 -
Copyright © 2020 LG Electronics Inc.
All rights reserved. Only training and service purposes.
Part 2
Outdoor Units

- 16 -
Copyright © 2020 LG Electronics Inc.
All rights reserved. Only training and service purposes.
• Function ........................................................................................17
ARU* Series

- 17 -
Function
1. Basic control ...................................................................................................................18
1.1 Normal operation .......................................................................................................18
1.2 Compressor control....................................................................................................18
1.3 EEV control ................................................................................................................19
2. Special control ................................................................................................................20
2.1 Oil return control ........................................................................................................20
2.2 Defrost ......................................................................................................................22
2.3 Stop operation............................................................................................................23
3. Protection control ...........................................................................................................24
3.1 Pressure protection control ........................................................................................24
3.2 Discharge temperature control...................................................................................25
3.3 Inverter protection control ..........................................................................................25
3.4 Phase detection .........................................................................................................25
4. Other control ...................................................................................................................26
4.1 Initial setup.................................................................................................................26
4.2 Pump Down ...............................................................................................................29
4.3 Night Low Noise Function ..........................................................................................30
4.4 Vacuum Mode ............................................................................................................31
4.5 Static pressure compensation mode..........................................................................31
4.6 Cycle Data View.........................................................................................................32
4.7 Refrigerant noise reduction mode..............................................................................33
4.8 Snow removal & rapid defrost....................................................................................34
4.9 Cool & Heat Selector (Only Heatpump) .....................................................................35
Function
Copyright © 2020 LG Electronics Inc.
All rights reserved. Only training and service purposes.

- 18 -
Copyright © 2020 LG Electronics Inc.
All rights reserved. Only training and service purposes.
Function
Note : Heating operation is not functional at an outdoor air temperature of 27 °C or more.
Cooling operation is not functional at an outdoor air temperature of 2 °C or less with indoor unit
combination of 10% or less
1.2 Compressor control
Fuzzy control : Maintain evaporating temperature(Te) to be constant on cooling mode and condensing
temperature(Tc) on heating mode by Fuzzy control to ensure the stable system performance.
[TC:47~51 °C(116.6~123.8 °F), Te:2~5 °C(35.6~41 °F)]
(1) Cooling mode
Te can be set various step at installation mode.
(2) Heating mode
Tc can be set various step at installation mode.
Note: By setting dip switch, Te and Tc are decided simultaneously.
1.1 Normal operation
1. Basic control
Compressor
Fan
Main EEV
Subcooling
Indoor Unit
EEV
EEV
Fuzzy control
Fuzzy control
Full open
Fuzzy control
Superheat fuzzy
control
Fuzzy control
Subcooling fuzzy control
Fuzzy control
Fuzzy control
Fuzzy control
Cooling operation Heating operationActuator
Stop
Stop
Min. pulse
Min. pulse
Min. pulse
Stop state
Fuzzy Control
Stop(0Hz)
Min. frequency
Fuzzy control start
Target
Inverter linear control as cooling and heating load increasing
System Capacity
Cooling and heating load
(Linear Control)
(Linear Control)
(Linear Control)
Inverter
Inverter
Compressor
Compressor
Inverter
Compressor

- 19 -
Copyright © 2020 LG Electronics Inc.
All rights reserved. Only training and service purposes.
1.3 EEV control
(1) Main EEV control
Main EEV operates with fuzzy control rules to keep the degree of super Heat(Superheat)
(about 3 ℃(37.4 ℉))at the evaporator outlet stable during heating mode
The degree of Superheat = Tsuction - Tevaporation
Tsuction : temperature at suction pipe sensor(℃,℉)
Tevaporation : evaporation temperature equivalent to low pressure(℃,℉)
(2) Subcooling EEV control(about 15 ℃(59 ℉))
Subcooling EEV works with fuzzy rules to keep the degree of Subcool at the outlet of subcooler during
cooling mode
The degree of Subcool = Tcondensation - Tliquid
Tliquid : temperature at outlet of subcooler(℃,℉)
Tcondensation : condensation temperature equivalent to high pressure(℃,℉)
(3) Avoiding excessive high discharge temperature : when main EEV opens some given opening and dis-
charge temperature is above 85 ℃(185 ℉) in heating operation, subcooling EEV may control the "sub-
cooling out temperature-evaporating temperature" to be some given difference.
Function

- 20 -
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2.1 Oil return control
2.1.1 Oil return control on cooling mode
Oil return operation recovers Oil level in compressor by collecting oil accumulated in pipe.
Each cycle component operates as shown on the below table during oil return operation.
nOil return operation time : 3 min for running step
nStarting condition : Every 8 hours operate
nOil return process ends if compressor protection control starts
OFF
40 pulse
Normal control
Normal control
Ending
ON
400 pulse
Normal control
Normal control
Running
OFF
40 pulse
Normal control
Normal control
Starting
Oil return signal
Thermo off unit EEV
Thermo on unit EEV
Fan
Component
Outdoor Unit
Indoor Unit
Min. pulse
Max. pulse
Normal control
30Hz
Ending
Min. pulse
Max. pulse
Normal control
Setting Value
Running
Min. pulse
Max. pulse
Normal control
30Hz
Starting
Subcooling EEV
Main EEV
Fan
Inverter compressor
Component
OFFOFF
OFFOFF
OFF
Heat Recovery : OFF
Heat pump : ON
4way valve 1
4way valve 2
2. Special control
Function