LG LT-B2461CL User manual

Ceiling Cassette
Air Conditioner
SERVICE MANUAL
MODELS: LT-B2461CL/LT-B2461HL
LT-B2861CL/LT-B2861HL
LT-B2421CL/LT-B2421HL
LT-B2821CL/LT-B2821HL
LT-B3021CL/LT-B3021HL
LT-B3681CL/LT-B3681HL
LT-B3621CL/LT-B3621HL
LT-B3661CL/LT-B3661HL

Contents
Functions 3
Product Specifications (Cooling & Heating) 5
Dimensions 8
Refrigeration Cycle Diagram 11
Wiring Diagram 13
Operation Details 19
Installation of Indoor, Outdoor Unit 22
Test Running 34
3-way Valve 36
Cycle Troubleshooting Guide 41
Electronic Parts Troubleshooting Guide 42
Electronic Control Device 46
Schematic Diagram 47
Exploded View and Replacement Parts List 49
–2–

Functions
• Room temperature sensor. (Thermistor)
• Maintains the room temperature in accordance with the Setting Temp.
• Indoor fan is delayed for 5 seconds at the starting.
• Restarting is inhibited for approx. 3 minutes.
• High, Med, Low
• Intermittent operation of fan at low speed.
• The louver can be set at swing up and down automatically.
• Although the air-conditioner is turned off by a power failure, it is restarted automatically previous operation
mode after power supply.
• The setting temperature and desired operation mode are automatically set by fuzzy rule.
• Both the indoor and outdoor fan stops during defrosting.
• Hot start after defrost ends.
• The indoor fan stops until the evaporator piping temperature will be reached at 28°C.
Indoor Unit
Operation ON/OFF by Remote controller
Sensing the Room Temperature
Room temperature control
Starting Current Control
Time Delay Safety Control
Indoor Fan Speed Control
Soft Dry Operation Mode
Airflow Direction Control
Auto Operation
Deice (Defrost) control (Heating)
Hot-start Control (Heating)
Auto Restart
–3–

–4–
Remote Controller
Operation ON/OFF
Operation Mode Selection
Fan Speed Selection
Room Temperature Display
Temperature Setting
Setting the Timer
Weekly Timer
(Cooling
model only) (Heating
model only)
(Low) (Med) (High)
Cooling Operation Mode ( )
Heating Operation Mode ( ) Auto Operation Mode ( )
Soft Dry Operation Mode ( )
Fan Operation Mode
HIMEDLO
Program Holiday
SET/CLR
MinHour
Week
Timer CancelTimer Cancel
: High:39°C ↔LOW:11°C
: Fan Operates without cooling & heating
Cooling Heating
Down to 18°C
Up to 30°CDown to 16°C
Up to 30°C

Product Specifications (Cooling & Heating)
1. 60Hz
Model Name
Item Unit
Cooling Capacity Btu/h(kcal/h)
Heating Capacity Btu/h(kcal/h)
Moisture Removal l/h
Power Source Ø, V, Hz
Indoor
Outdoor
Input Cooling
Heating
Running Current Cooling
Heating
E.E.R. Btu/h-W
Indoor
Outdoor
Net Weight Indoor kg
Outdoor
Refrigerant (R-22) g
Airflow Direction Control (Up & Down)
Remocon Type
Liquid
Gas
Drain Hose
Connecting Wire
Main Power Cable
Time Delay Safety Function
Air Circulation
Soft Dry
Fan Speed (Indoor)
Timer
Self-Diagnosis
Air Circulation m3/min
Dimensions
(W×H×D) mm
W
A
LT-
B2421CL
24,000(6,048)
–
3.5
17
50
2,700
–
12.5
–
8.89
60
2,000
24,000(6,048)
24,000(6,048)
3.5
17
50
2,700
2,400
12.5
10.5
8.89
61
1,870
28,000(7,056)
–
4.0
19
52
2,850
–
12.8
–
9.82
60
2,150
30,000(7,560)
–
4.3
19
52
2,850
–
12.8
–
10.53
60
2,150
30,000(7,560)
30,000(7,560)
4.3
19
52
2,850
2,750
12.8
12.3
10.53
65
2,400
28,000(7,056)
28,000(7,056)
4.0
19
52
2,850
2,750
12.8
12.3
9.82
65
2,400
LT-
B2421HL LT- B2821CL LT- B3021CL LT- B2821HL LT- B3021HL
–5–
Service Valve &
Connecting Tube
870 x 800 x 320
800 x 800 x 298(910 x 910 x 30)
35(30+5)
1Ø, 220V, 60Hz
870 x 655 x 320
O
Wired Remocon, Wireless Remocon(Optional)
3/8"(9.52)
5/8"(15.88)
O
0.75mm2↑
2.5mm2↑
O
O
O
3(Hi, Med, Low)
24Hrs
O

–6–
Model Name
Item Unit
Cooling Capacity Btu/h(kcal/h)
Heating Capacity Btu/h(kcal/h)
Moisture Removal ℓ/h
Power Source 󱇅, V, Hz
Indoor
Outdoor
Input Cooling
Heating
Running Current Cooling
Heating
E.E.R. Btu/h-W
Indoor
Outdoor
Net Weight Indoor kg
Outdoor
Refrigerant (R-22) g
Airflow Direction Control (Up & Down)
Remocon Type
Liquid
Gas
Drain Hose
Connecting Wire
Main Power Cable
Time Delay Safety Function
Air Circulation
Soft Dry
Fan Speed (Indoor)
Timer
Self-Diagnosis
Air Circulation m3/min
Dimensions
(W×H×D) mm
W
A
LT-B2461CL LT-B2461HL LT-B2861CL LT-B2861HL
24,000(6,048)
–
3.5
17
50
2,800
–
13.5
–
8.57
60
1,900
24,000(6,048)
24,000(6,048)
3.5
17
50
2,800
2,500
14
13
8.57
61
1,870
28,000(7,056)
–
4.0
19
52
2,850
–
13.4
–
9.82
60
2,100
28,000(7,056)
28,000(7,056)
4.0
19
52
2,850
2,650
13.4
12.6
9.82
65
2,400
Service Valve &
Connecting Tube
800 x 800 x 298(910 x 910 x 30)
1Ø, 220V~240V, 50Hz
35(30+5)
870 x 800 x 320
870 x 655 x 320
O
Wired Remocon, Wireless Remocon(Optional)
3/8"(9.52)
5/8"(15.88)
O
0.75mm2↑
2.5mm2↑
O
O
O
3(Hi, Med, Low)
24Hrs
O
2. 50Hz

–7–
Model Name
Item Unit
Cooling Capacity Btu/h(kcal/h)
Heating Capacity Btu/h(kcal/h)
Moisture Removal l/h
Power Source Ø, V, Hz
Indoor
Outdoor
Input Cooling
Heating
Running Current Cooling
Heating
E.E.R. Btu/h-W
Indoor
Outdoor
Net Weight Indoor kg
Outdoor
Refrigerant (R-22) g
Airflow Direction Control (Up & Down)
Remocon Type
Liquid
Gas
Drain Hose
Connecting Wire
Main Power Cable
Time Delay Safety Function
Air Circulation
Soft Dry
Fan Speed (Indoor)
Timer
Self-Diagnosis
Air Circulation m3/min
Dimensions
(W×H×D) mm
W
A
LT-
B3681CL
36,000(9,072)
–
5.0
22
58
4,300
–
7.5
–
–
80
3,150
36,000(9,072)
36,000(9,072)
5.0
22
58
4,300
4,100
7.5
7.0
–
81
3,150
36,000(9,072)
–
5.0
22
58
4,400
–
22
–
–
80
3,150
36,000(9,072)
36,000(9,072)
5.0
22
58
4,400
4,100
22
21
–
81
3,150
36,000(9,072)
36,000(9,072)
5.0
22
58
4,000
3,800
18
17
–
81
3,000
36,000(9,072)
–
5.0
22
58
4,000
–
18
–
–
80
3,150
LT-
B3681HL LT- B3661CL LT- B3661HL LT- B3621CL LT- B3621HL
Service Valve &
Connecting Tube
800 x 800 x 298(910 x 910 x 30)
35(30+5)
3Ø, 380-415V, 50Hz 1Ø, 220-240V, 50Hz 1Ø, 220V, 60Hz
790 x 965 x 320
O
Wired Remocon, Wireless Remocon(Optional)
3/8"(9.52)
3/4"(19.05)
O
0.75mm2↑
2.5mm2↑3.5mm2↑
O
O
O
3(Hi, Med, Low)
24Hrs
O

Dimensions
Indoor Unit
910
910
298
707
800
600113 65075
100
145423
910 255
29830
(328)
30
800 840
840
423
910
–8–

–9–
Outdoor Unit
Gas side
3-way valve
Liquid side
3-way valve
W
L6L7 L8 L9
L4
L11
L10
D
L1
L2
L5 L3
MODEL
DIM
W mm 870 870
H mm 655 800
D mm 320 320
L1 mm 370 370
L2 mm 25 25
L3 mm 340 340
L4 mm 630 775
L5 mm 25 25
L6 mm 546 546
L7 mm 162 162
L8 mm 162 162
L9 mm 54 54
L10 mm 74.5 74.5
L11 mm 79 79
LT-B2421CL/HL, LT-B2461CL/HL
LT-B2861CL, LT-B2821CL, LT-B3021CL LT-B2861HL, LT-B2821HL, LTB3021HL

–10–
Outdoor Unit(LT-B3621CL/HL, B3661CL/HL, B3681CL/HL)
320
790
385 72
482 4-ø12Hole
249
71
145 500 145
10 334
354
10
265
440
925
965
130
40
80
292.5
5
3
1
2
4
(Air intake vent)
(Air intake vent)
(Air intake vent)

Refrigeration Cycle Diagram
• COOLING ONLY
•Rated performance for refrigerant line length of: 5m
•If 24K or 28K Model is installed at a distance of 15m, 500g of refrigerant
should be added ....................................................(15-5)x50g
MODEL
24K, 28K, 30K BTU 5/8" 3/8" 5 20
36 K BTU 3/4" 3/8" 5 25
GAS LIQUID
515 50
520 70
Elevation B(m)
Length A(m) * Additional
refrigerant
(g/m)
Pipe Size
Rated Rated
Max. Max.
INDOOR UNIT OUTDOOR UNIT
HEAT
EXCHANGER
(EVAPORATOR)
HEAT
EXCHANGER
(CONDENSER)
COMPRESSOR
GAS SIDE
LIQUID SIDE
CAPILLARY TUBE
–11–

• HEAT PUMP
–12–
INDOOR UNIT OUTDOOR UNIT
HEAT
EXCHANGER HEAT EXCHANGER
COMPRESSOR
GAS SIDE
LIQUID SIDE
COOLING
HEATING
REVERSING
VALVE
CHECK VALVE
CAPILLARY TUBE
CAPILLARY TUBE
•Rated performance for refrigerant line length of: 5m
•If 24K or 28K Model is installed at a distance of 15m, 500g of refrigerant
should be added ....................................................(15-5)x50g
MODEL
24K, 28K, 30K BTU 5/8" 3/8" 5 20
36 K BTU 3/4" 3/8" 5 25
GAS LIQUID
515 50
520 70
Elevation B(m)
Length A(m) * Additional
refrigerant
(g/m)
Pipe Size
Rated Rated
Max. Max.

Wiring Diagram
(1) Indoor Unit
1. COOLING ONLY
2. HEAT PUMP
–13–

–14–
(2) Outdoor Unit
1. LT-B2461CL/B2861CL/B2421CL
B2821CL/B3021CL 2. LT-B2461HL/B2421HL
3. LT-B2861HL 4. LT-B2821HL/B3021HL
COMP.
MOTOR
R
S
C
RD BL
BL
P.T.C
(OPTION)
BR
BR
BRBL
BL
BL
FUSE(5A) FUSE(5A)
BL
YL
RD
POWER
RELAY 841
620
CAPACITOR
GN/YL
TO INDOOR
POWER INPUT
1(N)2(L)3(N)4(L) 5678
TERMINAL
BLOCK
GN/YL
OR
BR
BK
BR
COMP. MOTOR
RS
C
BL
BR
BR
BR
BR
BL
BL
BKBK
WH
BL
CRANK CASE
HEATER
FUSE(5A)
FUSE(5A)
BL
RD
YL
BK
OR
OR
BK
BK
RD
REVERSING
COIL
BK
BK
YL
BL
POWER
RELAY 841
620
Capacitor
HIGH PRESSURE S/W
GN/YL
L1L2L3
GN/YL
TO INDOOR
POWER INPUT
1(N)2(L)3(N)4(L) 5678
TERMINAL
BLOCK
3854A90002G
GN/YL BK
COMP. MOTOR
RS
C
BL
BR
BR
BR
BRBL
BL
WH
BL
FUSE(5A) FUSE(5A)
BL
RD
P.T.C
(OPTION)
BR
YL
OR
BK
BK
BK
BK
RD
REVERSING
COIL
BK
BK
YL
BL
POWER
RELAY 841
620
Capacitor Capacitor
HIGH PRESSURE S/W
GN/YL
L1L2L3
GN/YL
TO INDOOR
POWER INPUT
1(N)2(L)3(N)4(L) 5678
TERMINAL
BLOCK
3854A90002N
GN/YL BK
COMP. MOTOR
RS
C
BL
BR
BR
BR
BRBL
BL
WH
BL
FUSE(5A) FUSE(5A)
BL
RD
YL
OR
BK
BK
BK
BK
RD
REVERSING
COIL
BK
BK
YL
OR
BL
POWER
RELAY 841
620
Capacitor Capacitor
HIGH PRESSURE S/W
GN/YL
L1L2L3
GN/YL
TO INDOOR
POWER INPUT
1(N)2(L)3(N)4(L) 5678
TERMINAL
BLOCK
GN/YL BK

–15–
5. LT-B3681CL
THMO
C
H
L
TO INDOOR
Outdoor Unit Wiring Diagram
NOTE
BL : BLUE
BK : BLACK
BR : BROWN
OR : ORANGE GN/YL : GREEN/YELLOW
63H2
TMo
Co
HIGH PRESSURE SWITCH FOR HEATING
TERMINAL BLOCK
RUN CAPACITOR FOR FMo
TM
CM
MAIN TERMINAL BLOCK
COMPRESSOR
F1
FMo
FUSE (250V, 5A)
OUTDOOR FAN MOTOR
P/NO : 3854A30042P
RD : RED
WH :WHITE
YL :YELLOW WIRING OF FIELD
(CONNECTING WIRE)
TM
3Ø, 380-415V
POWER SUPPLY
BK
52C 13531
24632
B
A
BK
WH
BK
WH
RD
BK
BK
RD
BL BK
WH
T1 T3
T2
CM
WH
WH
BL
BK
RSTN
Co
OR YL BL BK OR YL BL BK
Co
FMo1FMo2
GN/YL
3(N)
4(L)
5
6
7
F1

–16–
6. LT-B3681HL
Outdoor Unit Wiring Diagram
NOTE
BL : BLUE
BK : BLACK
BR : BROWN
OR : ORANGE GN/YL : GREEN/YELLOW
63H2
C TH
20SV
52C
TMo
HIGH PRESSURE SWITCH FOR HEATING
THERMISTOR FOR PIPE TEMP.
REVERSING COIL
MAGNECTIC CONTACTOR
TERMINAL BLOCK
TM
52F1
CM
Co
FMo
MAIN TERMINAL BLOCK
RELAY FOR FMo
COMPRESSOR
RUN CAPACITOR FOR FMo
OUTDOOR FAN MOTOR
F1
DP
CH1
THMO
52F2
FUSE (250V, 5A)
DEICER PCB
CRANK CASE HEATER FOR CM
THEMOSTAT FOR COOLING
RELAY FOR FMO CONTROL.
P/NO : 3854A30042H
RD : RED
WH :WHITE
YL :YELLOW WIRING OF FIELD
(CONNECTING WIRE)
TM
3Ø, 380-415V
POWER SUPPLY
BK
63H2
52C 13531
24632
B
A
BK
WH BK TNS NO
C TH
NC
D.P
WH
T/B1
BK
WH
WH
RD
BK
WH BK
BK
RD
BL BK BK
WH
T1 T3
T2
CH1
CM
YL WH
WH
BL
BK
RSTN
Co
OR YL BL BK OR YL BL BK
Co
FMo1FMo2
20SV
BK
BK BK BK
WH YL
WH
YL
BL
BL
THMO
CL
H
GN/YL
TOO INDOOR
3(N)
4(L)
5
6
7
78
52F2
12
34
56
78
52F1
12
34
56
F1

–17–
7. LT-B3621CL/B3661CL
Outdoor Unit Wiring Diagram
NOTE
BL : BLUE
BK : BLACK
BR : BROWN
OR : ORANGE GN/YL : GREEN/YELLOW
52C
TMo
Co
MAGNETIC CONTACTOR
TERMINAL BLOCK
RUN CAPACITOR FOR FMo
TM
CM
CR
MAIN TERMINAL BLOCK
COMPRESSOR
RUN CAPACITOR FOR CM
F1
FMo
FUSE (250V, 5A)
OUTDOOR FAN MOTOR
P/NO : 3854A30042N
RD : RED
WH :WHITE
YL :YELLOW WIRING OF FIELD
(CONNECTING WIRE)
TM
POWER SUPPLY
BK
Cr
52C
BK
BK
L1
T1
L2
T2
B
A
WH
BK
WH
BK WH
BL BK BK
RD
RC
S
CM
WH
WH
GN/YL
WH
BL
BK
1
(
N
)
2
(
L
)
Co
OR YL BL BK OR YL BL BK
Co
FMo1FMo2
THMO
C
H
L
GN/YL
TO INDOOR
3(N)
4(L)
5
6
7
F1

–18–
8. LT-B3621HL/B3661HL
Outdoor Unit Wiring Diagram
NOTE
BL : BLUE
BK : BLACK
BR : BROWN
OR : ORANGE GN/YL : GREEN/YELLOW
63H2
C TH
20SV
52C
Cr
HIGH PRESSURE SWITCH FOR HEATING
THERMISTOR FOR PIPE TEMP.
REVERSING COIL
MAGNECTIC CONTACTOR
RUN CAPACITOR FOR CM
TM
52F1
CM
Co
FMo
MAIN TERMINAL BLOCK
RELAY FOR FMo
COMPRESSOR
RUN CAPACITOR FOR FMo
OUTDOOR FAN MOTOR
F1
DP
CH1
THMO
52F2
FUSE (250V, 5A)
DEICER PCB
CRANK CASE HEATER FOR CM
THEMOSTAT FOR COOLING
RELAY FOR FMO CONTROL.
P/NO : 3854A30042L
RD : RED
WH :WHITE
YL :YELLOW WIRING OF FIELD
(CONNECTING WIRE)
TM
POWER SUPPLY
BK
63H2
Cr
52C CH1
BK
BK BK
BK L1
T1
L2
T2
B
A
WH BK TNS NO
C TH
NC
D.P
WH
T/B1
BK
WH WH BK
WH
BL BK BK
RD
RC
S
CM
YL WH
WH
GN/YL
WH
BL
BK
1
(
N
)
2
(
L
)
Co
OR YL BL BK OR YL BL BK
Co
FMo1FMo2
20SV
BK
BK BK BK
WH YL
WH
YL
BL
BL
THMO
CL
H
GN/YL
TO INDOOR
3(N)
4(L)
5
6
7
78
52F2
12
34
56
78
52F1
12
34
56
F1

–19–
Operation Details
(1) The function of main control
1. Time Delay Safety Control
•3min... The compressor is ceased for 3minutes to balance the pressure in the refrigeration cycle.
(Protection of compressor)
•5sec... Vertical air flow direction control louvers open in 5 seconds to prevent noise between louvers and wind.
•30sec... The 4-way valve is ceased for 30sec. to prevent the refrigerant-gas abnormal noise when the Heating
operation is OFF or switched to the other operation mode while compress is off.
While compressor is running, it takes 3~5 seconds to switch.
2. Auto Swing Control
•This function is to swing the louver up and down automatically.
3. Air-Filter Checking Control
•'Filter' will display in the remote controller display when an air-filter is polluted. Then clean the air-filter for refer-
ence to Owners Manual.
4. Soft-Dry Operation
•The indoor fan speed is automatically set to the low, so the shift of the indoor fan speed is impossible because of
already being set to the best speed for Dry Operation by Micom Control.
5. Cooling Mode Operation
•When selecting the Cooling( ) Mode Operation, the unit will operate according to the setting by the remote con-
troller and the operation diagram is as following
Intake Air temp.
COMP. ON
(SET TEMP.+0.5°C)
COMP. OFF
(SET TEMP. -0.5°C) More than More than
3 minutes 3 minutes
Selecting Selecting Selecting
fan speed fan speed fan speed
COMPRESSOR ON OFF ON OFF ON
INDOOR FAN Low Low

Intake Air temp.
Setting temp.+3°C
(Compressor OFF)
Setting temp.
(Compressor ON)
INDOOR FAN Low OFF Low Low OFF
COMPRESSOR ON OFF ON OFF
•A point; While the indoor Heat-Exchanger temperature is higher than 35°C fan operates at low speed, when
it becomes lower than 35˚C fan stops.
•B point; When the indoor Heat-Exchanger temperature is higher than 35°C, fan operates at seleted fan
speed, when it becomes lower than 35°C, the fan operates at low speed for 10sec, after 10sec, it
operates at seleted fan speed.
–20–
6. Heating Mode Operation (Except Cooling Model)
The unit will operate according to the setting by the remote controller and the operation diagram is shown as following.
Hot Start Low
Selecting
Fan Speed
minimum 3min
Selecting fan
speed
minimum
10sec.
1min
AA
minimum
1min. minimum 10sec.
B
7. Hot-Start Control
•The indoor fan stops until the evaporator piping temperature will be reached to 28°C.
•The operation diagram is as following.
PIPING
TEMPERATURE 1min
COMPRESSOR
INDOOR FAN
ON
22°C
: Selected Fan : Low Fan : Fan Stop
25°C