Panasonic Cu 3ks19nbucu 4ksxxnbu Technical Service Manual

							5
2.  Installation Site Selection
2-1.  Indoor Unit
AVOID:

direct sunlight.

nearby heat sources that may affect performance of the
unit.

areas where leakage of flammable gas may be expected.

placing or allowing any obstructions near the air conditioner
inlet or outlet.

installing in rooms that contain instant-on (rapid-start) 
fluorescent lamps. (These may prevent the air conditioner
from receiving signals.)

places where large amounts of oil mist exist.

installing in locations where there are devices that 
generate high-frequency emissions.
DO:

select an appropriate position from which every corner of
the room can be uniformly air-conditioned. (High on a wall
is best for wall-mounted types.)

select a location that will hold the weight of the unit.

select a location where tubing and drain hose have the
shortest run to the outside. (Fig. 1)

allow room for operation and maintenance as well as 
unrestricted air flow around the unit. (Fig. 2a or 2b)

install the unit within the maximum elevation difference
(H1, H2, H3, H4) above or below the outdoor unit and
within a total tubing length (L1+L2+L3, L1+L2+L3+L4)
from the outdoor unit as detailed in Table 3 and Fig. 3a.
Drain hose Indoor unit
Outside drainage
Fig. 1
2 (5 cm)
min.
6 (15 cm)
min.
Front View2 (5 cm)
min.
Fig. 2a
For wall-mounted units
For ceiling-mounted cassette units
INDOOR
UNIT (1)
INDOOR
UNIT (4)INDOOR
UNIT (3)
INDOOR
UNIT (2) Tubing length (L1)
L2
L3
L4
H2
H3H4OUTDOOR
UNIT
Elevation
difference (H1)
Fig. 3a
WARNING
To prevent abnormal heat generation
and the possibility of fire, do not
place obstacles, enclosures and
grilles in front of or surrounding the
air conditioner in a way that may
block air flow.
Indoor unit
Floor levelWall
Minimum height 
from floor level
5 (1.5 m)
Fig. 3b

						

							6

install the indoor unit more than 3.3 (1 m) away from any
antenna or power lines or connecting wires used for tele-
vision, radio, telephone, security system, or intercom.
Electrical noise from any of these sources may affect
operation.

install in a sturdy manner to avoid increased operating
noise.
Table 3
*If total tubing length becomes 150 to 200 ft. (Max.) or 150 to 230 ft. (Max.), charge additional refrigerant (R410A) by 0.22 oz./ft.
No additional charge of compressor oil is necessary. For more detailed charging information, refer to the Technical & Service Manual.
Max. Max. Allowable Total  Limit of  Limit of Elevation Required Amount
Allowable Tubing  Length Total Tubing Length Difference of Additional
Model Tubing Length at Shipment (L1+L2+L3) or (H1, H2, H3, H4) Refrigerant
Per Unit (L1+L2+L3) or  (L1+L2+L3+L4) (ft.) (oz./ft.)
*(ft.) (L1+L2+L3+L4) (ft.)(ft.)
CU-3KS19NBU 82 150 (L1+L2+L3) 150 (L1+L2+L3) 50 —
CU-4KS24NBU 82 150 (L1+L2+L3+L4) 200 (L1+L2+L3+L4) 50 0.22
CU-4KS31NBU 100 150 (L1+L2+L3+L4) 230 (L1+L2+L3+L4) 50 0.22 
						

							7
Fig. 4b
Union 1/2(12.70mm)1/2(12.70
mm)
Flare 3/8(9.52
mm)
A joint for connecting tubes of
different sizes
(3/8(9.52
mm)     1/2(12.70mm)) Supplied Reducer
1/4(6.35mm)
1/4(6.35
mm)
1/4(6.35
mm) C
B
AOutdoor unit Indoor unit
(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U) (CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U)
(CS-MKS18NKU)
(CS-KS18NB4UW)
3/8(9.52mm)3/8(9.52
mm)
3/8(9.52
mm)
3/8(9.52
mm)
3/8(9.52
mm)
(A)
Fig. 4c
C
B
A(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U) (CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U) DOutdoor unit Indoor unit
3/8(9.52
mm)
3/8(9.52
mm)3/8(9.52
mm)
3/8(9.52
mm)
(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U)
3/8(9.52
mm)3/8(9.52
mm)
1/4(6.35
mm) 1/4(6.35
mm)
1/4(6.35
mm)
Union 3/8(9.52mm) Flare 1/2(12.70mm)
(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U)
1/2(12.70mm)3/8(9.52
mm)
1/4(6.35
mm) (1/2(12.70
mm)     3/8(9.52mm)) Supplied Reducer
(2) Connecting indoor unit for CU-4KS24NBU
(1) Connecting indoor unit for CU-3KS19NBU
Fig. 4a
3/8(9.52mm)3/8(9.52
mm)
1/4(6.35
mm)
1/4(6.35
mm)
1/4(6.35
mm)3/8(9.52
mm)
3/8(9.52
mm) 3/8(9.52mm)
3/8(9.52
mm)C
B
AOutdoor unit  Indoor unit 
(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U) (CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U)
(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U)
2-2.  Connecting Indoor Units
Figures (4a) – (4k) show the different types of indoor unit connections, including the use of a reducer.
To select the required indoor unit to be connected, refer to the Combination Table that was included in the
outdoor unit package.
(A)
(B) 
						

							8
(B)
Fig. 4d
C
B
A(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U) (CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U) DOutdoor unit Indoor unit
(CS-MKS18NKU)
(CS-KS18NB4UW)
1/2(12.70
mm)1/2(12.70
mm)
3/8(9.52
mm)
3/8(9.52
mm) 3/8(9.52mm)
3/8(9.52
mm)
(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U)
3/8(9.52
mm)3/8(9.52
mm)
1/4(6.35
mm) 1/4(6.35
mm)
1/4(6.35
mm) 1/4(6.35
mm)
(D)
Fig. 4f
Locally purchased
C
B(CS-MKS18NKU)
(CS-KS18NB4UW) D Outdoor unit Indoor unitUnion 1/2(12.70
mm) Flare 3/8(9.52mm) (3/8(9.52
mm)     1/2(12.70mm))
1/2(12.70mm)
3/8(9.52
mm)
(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U) 3/8(9.52mm)
3/8(9.52
mm)
1/4(6.35mm) 1/4(6.35
mm)
A
(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U)
3/8(9.52
mm)3/8(9.52
mm)
1/4(6.35
mm)
(CS-MKS18NKU)
(CS-KS18NB4UW)
1/2(12.70
mm)1/2(12.70
mm)
1/4(6.35
mm)
(C)
Fig. 4e
Union 5/8(15.88mm) Flare 1/2(12.70mm) (1/2(12.70
mm)     5/8(15.88mm)) Locally purchased
C
B(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U) (CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U) D Outdoor unit Indoor unit
(CS-MKS24NKU)
1/2(12.70mm)
3/8(9.52mm)
3/8(9.52
mm) 5/8(15.88
mm)
3/8(9.52
mm)
3/8(9.52
mm)
A
(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U)
3/8(9.52
mm)3/8(9.52
mm)
1/4(6.35
mm) 1/4(6.35
mm)
1/4(6.35
mm) 1/4(6.35
mm) 
						

							9
(A)
Fig. 4g
Union 3/8(9.52mm) Flare 1/2(12.70mm) (1/2(12.70
mm)     3/8(9.52mm)) Supplied Reducer
D
C(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U) Outdoor unit Indoor unit
(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U)
1/2(12.70mm)
1/2(12.70
mm)3/8(9.52
mm)
3/8(9.52
mm)
A
(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U)
B
(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U)
3/8(9.52
mm)3/8(9.52
mm)
3/8(9.52
mm)
3/8(9.52
mm)1/4(6.35
mm)
1/4(6.35
mm) 1/4(6.35
mm)
1/4(6.35
mm)
(3) Connecting indoor unit for CU-4KS31NBU
(B)
Fig. 4h
Union 3/8(9.52mm) Flare 1/2(12.70mm) (1/2(12.70
mm     3/8(9.52mm)) Supplied Reducer
AOutdoor unit Indoor unit
(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U)
3/8(9.52mm)3/8(9.52
mm)
1/4(6.35
mm)
B
(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U) 3/8(9.52mm)
3/8(9.52
mm)
1/4(6.35mm)
C
(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U)
1/2(12.70
mm)3/8(9.52
mm)
1/4(6.35
mm)
D
(CS-MKS18NKU)
(CS-KS18NB4UW) 1/2(12.70mm)
1/2(12.70
mm)
1/4(6.35mm)
(C)
Fig. 4i
A
(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U)
BOutdoor unit Indoor unit
(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U)
3/8(9.52
mm)
3/8(9.52
mm)3/8(9.52
mm)
3/8(9.52
mm) 1/4(6.35mm)
1/4(6.35
mm)
D
C(CS-MKS18NKU)
(CS-KS18NB4UW)
(CS-MKS18NKU)
(CS-KS18NB4UW) 1/2(12.70
mm)
1/2(12.70
mm)1/2(12.70
mm)
1/2(12.70
mm) 1/4(6.35mm)
1/4(6.35
mm) 
						

							10
(D)
Fig. 4j
Union 5/8(15.88mm) Flare 1/2(12.70mm) (1/2(12.70
mm)     5/8(15.88mm))Locally purchased
C
D
(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U) Outdoor unit Indoor unit
(CS-MKS24NKU)
Union 3/8(9.52mm) Flare 1/2(12.70mm)
(1/2(12.70
mm)     3/8(9.52mm))Supplied Reducer
1/2(12.70mm) 1/2(12.70
mm)5/8(15.88
mm)
3/8(9.52
mm)
A
(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U)
3/8(9.52
mm)3/8(9.52
mm)
1/4(6.35
mm)
B
(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U) 3/8(9.52mm)
3/8(9.52
mm)
1/4(6.35mm) 1/4(6.35
mm) 1/4(6.35
mm)
(E)
Fig. 4k
Union 5/8(15.88mm) Flare 1/2(12.70mm) (1/2(12.70
mm)     5/8(15.88mm)) Locally purchased
B
(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U)
AOutdoor unit Indoor unit
(CS-MKS7NKU,CS-MKS9NKU,CS-MKS12NKU)
(CS-MKS9NB4U,CS-MKS12NB4U)
3/8(9.52mm) 3/8(9.52
mm)
3/8(9.52mm) 3/8(9.52
mm)
1/4(6.35
mm) 1/4(6.35
mm)
C
(CS-MKS18NKU)
(CS-KS18NB4UW)
1/2(12.70
mm)1/2(12.70
mm)
1/4(6.35
mm)
D
(CS-MKS24NKU)
1/2(12.70
mm)5/8(15.88
mm)
1/4(6.35
mm) 
						

							2-3.  Outdoor Unit
AVOID:

heat sources, exhaust fans, etc. (Fig. 5a)

damp, humid or uneven locations.
DO:

choose a place as cool as possible.

choose a place that is well ventilated.

install in a location where at least two sides are unob-
structed, so that the flow of air at the intake port or
exhaust port is not blocked, and so that sufficient 
space is ensured for maintenance to be carried out 
without trouble. In general the top also must be unob-
structed. (Fig. 5b)

provide a solid base (level concrete pad, concrete block, 
6
14 (15 
40 cm) beams or equal), a minimum of 6
(15 cm) above ground level to reduce humidity and 
protect the unit against possible water damage and
decreased service life. (Figs. 5c and 5d)

install cushion rubber under unit’s feet to reduce vibration
and noise. (Fig. 5e)

use lug bolts or equal to bolt down unit, reducing vibration
and noise.

install in a location where no antenna of a television or
radio exists within 10 (3 m).
2-4.  Baffle Plate for the Outdoor Unit
It is recommended to use baffle plates.
When the outdoor unit is installed in a position exposed to
strong wind (such as seasonal winds with low air tempera-
ture in winter), baffle plates must be installed on the outdoor
unit. (Fig. 5f)
This unit is designed so that the fan of the outdoor unit runs
at low speed when the air conditioner is operated at low 
outdoor air temperatures. When the outdoor unit is exposed
to strong wind, the system pressure drops because of the
freeze protector.
Install a pair of windbaffle plates at the front and back of the
outdoor unit if it will be subject to strong wind during the
winter. (Figs. 5f, 5g, 5h, 5i, and 5j)
NOTE
Outdoor unitHot air
Heat source
Exhaust fanNO
Fig. 5a
Air intakeMin. 8" (20 cm)
Air discharge Min.4" (10 cm)Min.
1’8" (50 cm)
Valve
side
Min. 10"
(25 cm)
Min.
7' (2 m)Min.
7' (2 m)
Ground
Obstacle
Obstacle above
Air discharge
Min. 8" (20 cm)Air intake
Air intake
Concrete
or equal
About 6" (15 cm)
Min. 6" (15 cm) Anchor bolts
(4 pcs.)
About 16" (40 cm)
Cushion rubber
CAUTIONA solid base must not cover
the hole of the bottom plate.
Drain holes
Air discharge baffleWind
Front
Air intake baffle
No air intake baffle required on this side.Wind
BackFig. 5b
Fig. 5d
Fig. 5e Fig. 5c
Fig. 5f11 
						

							12
(1) Recommended dimensions of the baffle plates
D
F E CJH
L
I
BK Q R A
GO
(3-    6.5 mm)
3-    1/4"
(2-    6 mm) 2-    15/64"
AB
H
C
E
FK I
J
G G
D
(4-    6.5 mm)4-    1/4"
Fig. 5h
For Air Intake
For Air Discharge
Material to be used:  Metal plate with corrosion protection treatment
Plate thickness: 0.0394 to 0.0472 (1.0 to 1.2 mm)
(2) Parts required (field supply except for screws)
Dimensions
ABCDE FGH I J K LOQR
Model
CU-3KS19NBU,(inch)25-3/16 25/32 1-31/32 25 10-5/8 10-5/8 25/64 25/32 19/32 25-7/8 19/64 25/64 5-29/32 25/32 25/32
CU-4KS24NBU
(mm) 640 20 50 635 270 270 10 20 15 657 7.5 10 150 20 20
CU-4KS31NBU(inch)25-3/16 25/32 1-3/830-29/32 13-25/32 13-25/3225/64 25/32 19/3231-25/3219/64 25/64 5-29/32 25/32 25/32
(mm) 640 20 35 785 350 350 10 20 15 807 7.5 10 150 20 20
Dimensions
ABCDE FGH I J K
Model
(inch)22-1/16 23-1/32 13-25/32 5-29/32 19-9/32 1-3/8 2-5/32 18-5/16 2-3/8 3-11/32 31/32
(mm) 560 585 350 150 490 35 55 465 60 85 25
Air Intake BaffleAir Discharge Baffle
Fig. 5g
Item Q’ty Remarks
Baffle plate 1
Screw 5/32 
15/32 (4 
12 mm) tapping 2 Attached to outdoor unit
Bolt 15/64 
19/32 – 25/32 (M6 
15 – 20 mm) 3
Nut 15/64 (M6) 3
Washer 3
Spring washer 3
Item Q’ty Remarks
Baffle plate 1
Bolt 15/64 
13/32 – 19/32 (M6 
10 – 15 mm)  4
Nut 15/64 (M6) 4
Washer 4
Spring washer 4
Air Intake BaffleAir Discharge Baffle
CU-3KS19NBU
CU-4KS24NBU
CU-4KS31NBU 
						

							13
(3) Installation procedure
Panel top
Panel front Panel side R
Panel side L
1. Air Intake Baffle
(1) Left side
1. Remove the top panel from the unit.
2. Remove the panel side L, and drill 3 holes of ø1/4 inch
(6.5 mm) at the prescribed position.
3. Install the windbaffle on the unit using field supply bolts
and nuts.
4. Recommended bolts to be used are 15/64 (M6 ISO 
standard), and the recommended length of the bolts is
between 19/32 – 25/32 inch (15 – 20 mm).
5. Use washers and spring washers to tightly fasten the
windbaffle to the unit.
(2) Right side
1. Remove the top panel from the unit.
2. Use 2 preholes on the panel side R to install the baffle
plate.
3. Remove the panel side R from the unit by removing the
screws. These screws are used in step 4 below.
4. Put (sandwich) the windbaffle between the unit and the
panel side R, then install the windbaffle on the unit using
the above screws. Be careful not to damage the screw
holes.2. Air Discharge Baffle
1. Remove the panels front, top, side L and R from the
unit and drill 4 holes of ø1/4 inch (6.5 mm) at the 
prescribed positions.
2. Install the windbaffle on the unit using field supply
bolts and nuts.
3. Recommended bolts to be used are 15/64 (M6 ISO 
standard), and the recommended length of the bolts 
is between 13/32 – 19/32 inch (10 – 15 mm).
4. Use washers and spring washers to tightly fasten the
windbaffle to the unit.
(4) Precautions for installation
1. Be sure not to damage painted surfaces.
2. Finish the edges of the windbaffle to avoid cuts or injury.
3. Drilling of holes must be carefully done so that no damage is caused to external or internal parts of the unit. 
Particular care must be taken that drill chips do not drop into the unit.

In order to prevent contact of the bolts and heat exchanger and other parts inside the unit, install the windbaffle using
bolts from inside the unit and fasten the bolts with nuts from outside the unit.

When the windbaffle is installed on the unit, the unit has higher wind resistance. In order to prevent the unit from
falling over, anchor the legs of the unit using anchor bolts (or similar method).
NOTE
Panel side R
Panel top
Panel front
Panel side L
Fig. 5i Fig. 5j 
						

							14
Fig. 6a
23-15/165-11/32
15/32
35-7/16 (900)
13-19/32 12-19/32
14-17/32
2-29/32
29-1/8 (740) 23/32
1-13/16
2-1/165-29/322-27/32
2-3/42-1/324-7/16
2-15/162-3/44-1/2
A
Service valve on narrow tube side
(Outer diameter 1/4"(
6.35))
Service valve on wide tube side
(Outer diameter 3/8"(
9.52))A
(1) CU-3KS19NBU
Fig. 6b
23-15/165-11/32
15/32
12-19/32
13-19/32
14-17/32
35-7/16 (900)
29-1/8 (740)
2-1/16 1-13/16 2-29/32
2-13/32
A
4-1/2 2-1/325-29/322-27/32
2-3/4
4-7/16
2-15/162-3/4
Service valve on narrow tube side
(Outer diameter 1/4(6.35))
Service valve on wide tube side
(Outer diameter 3/8(9.52)) Service valve on wide tube side
(Outer diameter 1/2(12.70))
A
23/32
Fig. 6c
23-15/16
15/32
12-19/32
13-19/32
14-17/32
5-11/32
35-7/16 (900)
23/32
35-1/32 (890)
2-29/32
2-1/16 1-13/16
2-13/324-1/2 2-1/32
4-7/165-29/32
2-15/162-27/32
2-3/4
2-3/4
A
Service valve on narrow tube side
(Outer diameter 1/4(6.35))
Service valve on wide tube side
(Outer diameter 1/2(12.70))
Service valve on wide tube side
(Outer diameter 3/8(9.52))A
(2) CU-4KS24NBU
(3) CU-4KS31NBU
2-5.  Outer Dimensions of Outdoor Unit
unit: inch (mm)