Mitsubishi Electric BRANCH BOX PAC-MKA53BC Operating manual

March 2023
SPLIT-TYPE, HEAT PUMP AIR CONDITIONERS
TECHNICAL & SERVICE MANUAL
CONTENTS
1. SAFETY PRECAUTION··································· 2
2. OVERVIEW OF UNIT······································ 5
3. SPECIFICATIONS ·········································· 8
4. OUTLINES AND DIMENSIONS························· 9
5. WIRING DIAGRAM········································10
6 . NECESSARY CONDITIONS FOR SYSTEM CONSTRUCTION ············ 11
7. TROUBLESHOOTING····································15
8. DISASSEMBLY PROCEDURE·························24
BRANCH BOX
HFC
utilized
R410A
Note:
• This service manual
describes technical data of
branch box. As for indoor
units and outdoor unit,
refer to its service manual.
PARTS CATALOG (OCB801)
PAC-MKA53BC
No. OCH801
[Service Ref.]
PAC-MKA33BC
PAC-MKA53BC
[Model Name]
<Branch box>
PAC-MKA33BC
PAC-MKA53BC

2
OCH801
1SAFETY PRECAUTION
Cautions for units utilizing refrigerant R410A
1-1. CAUTIONS RELATED TO NEW REFRIGERANT
Use new refrigerant pipes.
Avoid using thin pipes.
Use a vacuum pump with a reverse ow check
valve.
Vacuum pump oil may ow back into refrigerant cycle and
that can cause deterioration of refrigerant oil, etc.
Handle tools with care.
If dirt, dust or moisture enters into refrigerant cycle, that
can cause deterioration of refrigerant oil or malfunction of
compressor.
Do not use a charging cylinder.
If a charging cylinder is used, the composition of refrigera-
nt will change and the e󰀩ciency will be lowered.
Use the specied refrigerant only.
Never use any refrigerant other than that specied.
Doing so may cause a burst, an explosion, or re when
the unit is being used, serviced, or disposed of.
Correct refrigerant is specied in the manuals and on the
spec labels provided with our products.
We will not be held responsible for mechanical failure,
system malfunction, unit breakdown or accidents caused
by failure to follow the instructions.
Ventilate the room if refrigerant leaks during
operation. If refrigerant comes into contact with
a ame, poisonous gases will be released.
Use the following tools specically designed for
use with R410A refrigerant.
The following tools are necessary to use R410A
refrigerant.
Tools for R410A
Gauge manifold Flare tool
Charge hose Size adjustment gauge
Gas leak detector Vacuum pump adaptor
Torque wrench Electronic refrigerant
charging scale
Make sure that the inside and outside of refrige-
rant piping is clean and it has no contaminants
such as sulfur, oxides, dirt, shaving particles,
etc., which are hazard to refrigerant cycle.
In addition, use pipes with specied thickness.
Contamination inside refrigerant piping can cause deterio-
ration of refrigerant oil, etc.
Store the piping indoors, and keep both ends of
the piping sealed until just before brazing.
(Leave elbow joints, etc. in their packaging.)
If dirt, dust or moisture enters into refrigerant cycle, that
can cause deterioration of refrigerant oil or malfunction of
compressor.
The refrigerant oil applied to are and ange
connections must be ester oil, ether oil or
alkylbenzene oil in a small amount.
If large amount of mineral oil enters, that can cause
deterioration of refrigerant oil, etc.
Charge refrigerant from liquid phase of gas
cylinder.
If the refrigerant is charged from gas phase, composition
change may occur in refrigerant and the e󰀩ciency will be
lowered.
Do not use refrigerant other than R410A.
If other refrigerant (R22, etc.) is used, chlorine in refrige-
rant can cause deterioration of refrigerant oil, etc.
Precautions during the repair service
• Do not perform the work involving the electric parts
with wet hands.
• Do not pour water into the electric parts.
• Do not touch the refrigerant.
•
Do not touch the hot or cold areas in the refrigerating cycle.
• When the repair or the inspection of the circuit needs
to be done without turning o󰀨 the power, exercise great
caution not to touch the live parts.
Preparation before the repair service
• Prepare the proper tools.
• Prepare the proper protectors.
• Provide adequate ventilation.
• After stopping the operation of the air conditioner, turn
o󰀨 the power-supply breaker.
• Discharge the condenser before the work involving the
electric parts.

3
OCH801
Electronic weighing scale
Unit
[3] Service tools
(1) Use the below service tools as exclusive tools for R410A refrigerant.
[2] Additional refrigerant charge
When charging directly from cylinder
(1) Check that cylinder for R410A on the market is a syphon type.
(2) Charging should be performed with the cylinder of syphon stood vertically. (Refrigerant is charged from liquid phase.)
[1] Cautions for service
(1) Perform service after recovering the refrigerant left in unit completely.
(2) Do not release refrigerant in the air.
(3) After completing service, charge the cycle with specified amount of refrigerant.
(4) If moisture or foreign matter might have entered the refrigerant piping during service, ensure to remove them.
No. Tool name Specifications
Gauge manifold · Only for R410A · Use the existing fitting specifications. (UNF1/2)
· Use high-tension side pressure of 5.3MPa·G or over.
Charge hose · Only for R410A
· Use pressure performance of 5.09MPa·G or over.
Electronic weighing scale
Gas leak detector · Use the detector for R134a, R407C or R410A.
Adaptor for reverse flow check · Attach on vacuum pump.
Refrigerant charge base
Refrigerant cylinder · Only for R410A · Top of cylinder (Pink)
· Cylinder with syphon
Refrigerant recovery equipment

OCH801 4
(2) Cautions for refrigerant piping work
New refrigerant R410A is adopted for replacement inverter series. Although the refrigerant piping work for R410A is same
as for R22, exclusive tools are necessary so as not to mix with different kind of refrigerant. Furthermore as the working
pressure of R410A is 1.6 times higher than that of R22, their sizes of flared sections and flare nuts are different.
Thickness of pipes
Because the working pressure of R410A is higher compared to R22, be sure to use refrigerant piping with thickness
shown below. (Never use pipes of 0.7 mm or below.)
Dimensions of flare cutting and flare nut
The component molecules in HFC refrigerant are smaller compared to conventional refrigerants. In addition to that,
R410A is a refrigerant, which has higher risk of leakage because its working pressure higher than that of other refriger-
ants. Therefore, to enhance airtightness and strength, flare cutting dimension of copper pipe for R410A has been speci-
fied separately from the dimensions for other refrigerants as shown below. The dimension B of flare nut for R410A also
has partly been changed to increase strength as shown below. Set copper pipe correctly referring to copper pipe flaring
dimensions for R410A below. For 1/2” and 5/8” inch pipes, the dimension B changes.
Use torque wrench corresponding to each dimension.
Tools for R410A (The following table shows whether conventional tools can be used or not.)
1/4
3/8
1/2
5/8
3/4
ø6.35
ø9.52
ø12.70
ø15.88
ø19.05
0.8
0.8
0.8
1.0
—
0.8
0.8
0.8
1.0
1.0
Nominal
dimensions (in)
Diagram below: Piping diameter and thickness
Outside
diameter (mm)
Thickness (mm)
R410A R22
1/4
3/8
1/2
5/8
3/4
ø6.35
ø9.52
ø12.70
ø15.88
ø19.05
9.1
13.2
16.6
19.7
—
9.0
13.0
16.2
19.4
23.3
Nominal
dimensions (in)
Flare cutting dimensions
Outside
diameter (mm)
Dimension A ( )
+0
-0.4 (mm)
R410A R22 1/4
3/8
1/2
5/8
3/4
ø6.35
ø9.52
ø12.70
ø15.88
ø19.05
17.0
22.0
26.0
29.0
—
17.0
22.0
24.0
27.0
36.0
Nominal
dimensions (in)
Flare nut dimensions
Outside
diameter (mm
)Dimension B (mm)
R410A R22
Gauge manifold
Charge hose
Gas leak detector
Refrigerant recovery equipment
Refrigerant cylinder
Applied oil
Safety charger
Charge valve
Vacuum pump
Flare tool
Bender
Pipe cutter
Welder and nitrogen gas cylinder
Refrigerant charging scale
Vacuum gauge or thermis-
tor vacuum gauge and
vacuum valve
Charging cylinder
Air purge, refrigerant charge
and operation check
Gas leak check
Refrigerant recovery
Refrigerant charge
Apply to flared section
Prevent compressor malfunction
when charging refrigerant by
spraying liquid refrigerant
Prevent gas from blowing out
when detaching charge hose
Vacuum drying and air
purge
Flaring work of piping
Bend the pipes
Cut the pipes
Weld the pipes
Refrigerant charge
Check the degree of vacuum. (Vacuum
valve prevents back flow of oil and refri-
gerant to thermistor vacuum gauge)
Refrigerant charge
Tool exclusive for R410A
Tool exclusive for R410A
Tool for HFC refrigerant
Tool exclusive for R410A
Tool exclusive for R410A
Ester oil and alkylbenzene
oil (minimum amount)
Tool exclusive for R410A
Tool exclusive for R410A
Tools for other refrigerants can
be used if equipped with adop-
ter for reverse flow check
Tools for other refrigerants
can be used by adjusting
flaring dimension
Tools for other refrigerants can be used
Tools for other refrigerants can be used
Tools for other refrigerants can be used
Tools for other refrigerants can be used
Tools for other refrigerants
can be used
Tool exclusive for R410A
Tools and materials Use R410A tools Can R22 tools be used?
(Usable if equipped
with adopter for rever-
se flow)
(Usable by adjusting
flaring dimension)
Can R407C tools be used?
Ester oil:
Alkylbenzene oil: minimum amount
(Usable if equipped
with adopter for rever-
se flow)
(Usable by adjusting
flaring dimension)
: Prepare a new tool. (Use the new tool as the tool exclusive for R410A.)
: Tools for other refrigerants can be used under certain conditions.
: Tools for other refrigerants can be used.
Dimension A
Dimension B

5
OCH801
2OVERVIEW OF UNIT
Indoor unit (Ceiling concealed type)
Indoor unit
(Wall mounted type)
Outdoor unit Branch box
2-1. SYSTEM OUTLINE
The additional connection of the branch box together with employment of the compact trunk-looking outdoor unit can
successfully realize a long distance piping for big houses. Equipped with a microprocessor, the branch box can translate
the transmission signal of indoor units to achieve the optimum control.
2-1-1. System example
2-1-2. Method for identifying
Branch box (Controller)
Number of branches
5: 5 branches
3: 3 branches
Model type
Model type
P A C – MKA 5 3 BC
(Indispensable)
Optional parts
Development No. : A, B, ···,etc.
Power supply
Single phase 220/230/240 V, 50 Hz
Multi type heat pump
inverter outdoor unit
Indicates equivalent to rated cooling capacity.
(kBTU/h)
Number of connectable indoor units (MAX.)
Control and refrigerant
A : New A control and R410A
M X Y-
100 4 C V A
■ Branch box

6
OCH801
2-2. INSTALLATION
Space required for Installation and servicing for branch box for PAC-MKA53/33BC
(1) Front View (Fig. 2-1)
Branch box
On the side of piping
(2) Side View (Fig. 2-2, Fig. 2-3, Fig. 2-4)
For indoor installations
Ceiling board
Maintenance hole
Reactor box (Optional parts)
*1: A minimum 350 mm is required for 90° bends in refrigerant piping.
*2: is “Min 200 mm”.
In the case of less than 200 mm (for example is 100 mm), the exchange work of branch box from a maintenance hole
becomes difficult (Only exchange work of a PCB, linear expansion valve coils and sensors is possible).
To install the optional reactor box, set to Min 270 mm <recommendation>. (Fig. 2-4)
*3: is “□ 600 mm”.
In the case of “□ 450 mm”, prepare a maintenance hole at a PCB side (as it is shown in Fig. 2-3, Fig. 2-4), and “Min 300
mm” is needed as distance .
In the case of less than 300 mm (for example is 100 mm), the exchange work of Branch box, linear expansion
valve coils and sensors from a maintenance hole becomes difficult. Only exchange work of a PCB is possible.
(3) Top View (Fig. 2-5)
NOTE 1: The branch box is only for indoor use.
NOTE 2: Please attach the special optional cover to install branch box outdoors.
Fig. 2-5
Fig. 2-3
Fig. 2-2Fig. 2-1
Unit: mm
(3)
Min 250
(1) (2)
50 450
� 450
250 250 250
170 30
278
180-200
*1
*3
*2
A
B
C
D
DE
E
450
ED
F
Fig. 2-4

7
OCH801
Branch box
■ In the case of using 1-branch box
Flare connection employed
2 branches pipe (joint)
: optional parts
Branch box #1
Branch box #2
■ In the case of using 2-branch boxes
■ Installation procedure (2 branches pipe (joint))
Refer to the installation manuals of MSDD-50AR-E and MSDD-50BR-E.
2-3. SIMPLIFIED PIPING SYSTEM
The piping connection size differs according to the type and capacity of outdoor/indoor units.
Match the piping connection size of branch box with outdoor/indoor unit.
If the piping connection size of branch box does not match the piping connection size of outdoor/indoor unit,
use optional different-diameter (deformed) joints to the branch box side.
(Connect deformed joint directly to the branch box side.)

8
OCH801
3 SPECIFICATIONS
Model name PAC-MKA53BC PAC-MKA33BC
Connectable number of indoor units Maximum 5 Maximum 3
Power supply Single phase, 208/230 V, 60 Hz
Input kW 0.003
Running current A 0.15
External nish Galvanized sheets
Dimensions Width in (mm) 17-23/32 (450)
Depth in (mm) 11-1/32 (280)
Height in (mm) 6-11/16 (170)
Weight lb (kg) 16 (7.4) 15 (6.7)
Piping
connection
(Flare)
Branch (indoor side)* Liquid in (mm) 1/4 (ø6.35) × 5 {A,B,C,D,E} 1/4 (ø6.35) × 3 {A,B,C}
Gas in (mm) 3/8 (ø9.52) × 4 {A,B,C,D}, 1/2 (ø12.7) × 1 {E} 3/8 (ø9.52) × 3 {A,B,C}
Main (outdoor side) Liquid in (mm) 3/8 (ø9.52)
Gas in (mm) 5/8 (ø15.88)
* The piping connection size differs according to the type and capacity of indoor units. Match the piping connection size for indoor and branch box.
If the piping connection size of branch box does not match the piping connection size of indoor units, use optional different-diameter (deformed)
joints to the branch box side. (Connect deformed joint directly to the branch box side.)

9
OCH801
4OUTLINES AND DIMENSIONS
Unit: mm(inch)
PAC-MKA33BC
PAC-MKA53BC
TO INDOOR UNIT
AABC B
C
CAP
CAP
25
〈1〉
72
〈2-27/32〉
90
〈3-17/32〉
170〈6-11/16〉
47〈1-27/32〉
65
〈2-9/16〉
25
〈1〉
25
〈1〉
70
〈2-3/4〉
70
〈2-3/4〉
209〈8-7/32〉
450〈17-23/32〉
SUSPENSION BOLT PITCH
SUSPENSION BOLT PITCH
320〈12-19/32〉
402〈15-13/16〉
24〈1〉
12〈1/2〉1/2 inch Conduit
attachment
When installing the conduit.
Set the attachment to the
inner side of each panel.
(1:2)
5-ø22〈7/8〉
28
〈1-3/32〉
20
〈25/32〉
58〈2-9/32〉
24
〈15/16〉
105
〈4-1/8〉
12〈15/32〉
15〈19/32〉
66〈2-19/32〉
24
〈15/16〉
48〈1-7/8〉48〈1-7/8〉
17〈21/32〉
129〈5-3/32〉
5-ELECTRIC WIRE INLET
CONDUIT PLATE
CONTROL COVER
TO OUTDOOR UNIT
SERV ICE PANEL
(for LEV, THERMISTOR)
40〈1-17/32〉
280〈11-1/32〉
87
〈3-7/16〉70 〈2-3/4〉
83
〈3-9/32〉
96
〈3-25/32〉
112
〈4-3/8〉
TERMINAL BLOCK
TO M-NET UNIT
TERMINAL BLOCK
TO INDOOR UNIT
TERMINAL BLOCK
TO OUTDOOR UNIT
TB2B
TB5
TB3B
TB3CTB3A
SUSPENSION BOLT: W3/8(M10)
GAS PIPE
REFRIGERANT PIPE FLARED CONNECTION
1/4F 1/4F 1/4F 3/8F
3/8F 3/8F 3/8F 5/8F
TO OUTDOOR UNIT
LIQUID PIPE A B C Unit: inch
E D C B A
E D C B A
TO INDOOR UNIT
90
〈3-17/32〉
70
〈2-3/4〉
70
〈2-3/4〉
70
〈2-3/4〉
70
〈2-3/4〉
450〈17-23/32〉
67〈2-9/16〉
25
〈1〉
25
〈1〉
25
〈1〉
25
〈1〉
25
〈1〉
65
〈2-9/16〉47〈1-27/32〉
170〈6-11/16〉
72
〈2-27/32〉
5-ø22〈7/8〉
(1:2)
When installing the conduit.
Set the attachment to the
inner side of each panel.
1/2 inch Conduit
attachment
129〈5-3/32〉
17〈21/32〉48〈1-7/8〉48〈1-7/8〉
24
〈15/16〉
66〈2-19/32〉
15〈19/32〉
12〈15/32〉105
〈4-1/8〉
24
〈15/16〉
58〈2-9/32〉
20
〈25/32〉28 〈1-3/32〉
SUSPENSION BOLT PITCH
SUSPENSION BOLT PITCH
320〈12-19/32〉
12〈1/2〉
24〈1〉
402〈15-13/16〉
5-ELECTRIC WIRE INLET
CONDUIT PLATE
CONTROL COVER
SERVICE PANEL
(for LEV, THERMISTOR)
TO OUTDOOR UNIT
40〈1-17/32〉280〈11-1/32〉
83
〈3-9/32〉
96
〈3-25/32〉
112
〈4-3/8〉
70
〈2-3/4〉
87
〈3-7/16〉
EDCBA
LIQUID PIPE TO OUTDOOR UNIT
5/8F1/2F3/8F3/8F
3/8F
3/8F 3/8F1/4F1/4F1/4F1/4F1/4F
REFRIGERANT PIPE FLARED CONNECTION
GAS PIPE
SUSPENSION BOLT: W3/8(M10)
TB3B TB3D
TB3A TB3C TB3E
TB5 TB2B
TERMINAL BLOCK
TO OUTDOOR UNIT
TERMINAL BLOCK
TO INDOOR UNIT
TERMINAL BLOCK
TO M-NET UNIT
Unit: inch

10
OCH801
5WIRING DIAGRAM

11
OCH801
6
NECESSARY CONDITIONS FOR SYSTEM CONSTRUCTION
6-1. TRANSMISSION SYSTEM SETUP
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
Branch box
001 Branch box
006
A-Control
Indoor
A
(001)
B
(002)
C
(003)
A
(006)
B
(007)
C
(008)
D
(004)
E
(005)
M-NET cable
①M-NET cable shielded wire must
be connected to each refrigerant
system (outdoorand branch box).
②Set addresses: Make sure that
the address is not the same as any other address
Outdoor unit ............051–100 Branch box ............... 001–046
③Outdoor unit has no 100s digit
switch. The address automatically
become "100" if it is set as "01–50".
Piping
Signal line
④Make sure that the wiring between the
branch box and indoor unit is properly done, matching with the piping connection.
A B C D E A B C
MA remote
controller MA remote
controller MA remote
controller MA remote
controller
Wireless
remote
controller
Wireless
remote
controller
Wireless
remote
controller
Wireless
remote
controller
For centralized management 051
Outdoor unit Piping
For Branch box
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
Address SW 0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
Address SW
SW1
ON
123456
SW1
ON
123456
⑤M-NET remote controller cannot be connected
with refrigerant system including branch box.
⑥Refrigerant systems including branch box cannot be
grouped with using M-NET remote controller or system controller.
A-Control
Indoor A-Control
Indoor A-Control
Indoor A-Control
Indoor A-Control
Indoor A-Control
Indoor A-Control
Indoor
①
② ③
④

12
OCH801
Capillary
tube Capillary tube
E
D
C
B
A
Strainer
#100
Strainer
#100
Thermistor (TH-A–E)
(Gas pipe temperature)
LEV A–E
(Linear expansion valve)
C
B
A
Strainer
#100
Strainer
#100
Thermistor (TH-A–C)
(Gas pipe temperature)
LEV A–C
(Linear expansion valve)
PAC-MKA53BC
PAC-MKA33BC
Branch box
Capillary tube behind LEV
(in cooling mode)
(ø0.157 × ø0.117 × L(5-1/8)) × 5
(ø4 × ø3.0 × L130) × 5
(ø0.157 × ø0.117 × L(5-1/8)) × 3
(ø4 × ø3.0 × L130) × 3
Unit: mm
■PAC-MKA53BC ■PAC-MKA33BC
6-2. REFRIGERANT SYSTEM DIAGRAM

13
OCH801
6-3. TYPICAL CONTROL SYSTEM
TB7
TB3
(51)
L 3
L
1
OC
TB7
(53)
OC
24 VDC
L 4
L 5
M1M2
S
M1M2
S
S
M1M2
S
TB3
M1M2 S
M1M2
S
M1M2
TB3A
A-IC
(01)
A-IC
(02)
A-IC
(03)
A-IC
(04)
A-IC
MA-RC
MA-RC
MA-RC
MA-RC
WL-RC
WL-RC
WL-RC
WL-RC
(05)
A-IC
(06)
A-IC
(07)
A-IC
(08)
S1
S2
S3
TB
S1
S2
TB5/TB15
1
2A B
A
B
A
B
A
B
TB5/TB15
1
2
TB5/TB15
1
2
TB5/TB15
1
2
S3
TB
S1
S2
S3
TB
S1
S2
S3
TB
S1
S2
S3
TB
S1
S2
S3
TB
S1
S2
S3
TB
S1
S2
S3
TB
S1
S2
S3
TB3B
S1
S2
S3
TB3C
S1
S2
S3
TB3D
S1
S2
S3
TB3E
S1
S2
S3
TB3A
S1
S2
S3
TB3B
S1
S2
S3
TB3C
S1
S2
S3
M1
M2
S
TB5
M1
M2
S
TB5
L
2
Power
Supply
Unit
System
controller
Branch Box
Branch Box
: Shielded wire
( ): Address example
A
A
A
(01)
(06)
A
Note: M-NET remote controller cannot be connected with a refrigerant system which includes branch box.
(1) Di󰀨erence between display and operation
When operating the system using the system controller, details of those operations will not appear on the display of the
wireless remote controller.
The set temperature range is di󰀨erent in the wireless remote controller that comes with room air conditioner and the system
controller. The room air conditioner has a wider range. If the target temperature is set to below 63°F [17°C] or less, or 86°F
[30°C] or more by the wireless remote controller that comes with room air conditioner, the temperature displayed on the
system controller may be converted to their maximum/minimum set temperature. For instance, when HEAT operation at
61°F [16°C] is set at the room air conditioner, the system controller may display 63°F [17°C].
When DRY mode is set with the wireless remote controller, the room air conditioner automatically set the optimum target
temperature. The system controller will display the target temperature as a set temperature.
When DRY mode is set with the system controller, the room air conditioner performs DRY mode control operation according
to the temperature set with the system controller.
(2) Timer operation
Timer operation should be set using only 1 controller from the remote controller that comes with the room air conditioner,
the system controller or the MA remote controller. If more than 1 controller is used to set the timer at the same time, the
timer will not function properly.
When the timer is set with the wireless remote controller; the system controller will not show the timer display.
The timer set with the system controller will not be cancelled with the wireless remote controller.
(3) Manual operation prohibition
When the manual operation (ON/OFF, set temperature, or operation mode) is prohibited with the system controller, the
command to perform the prohibited operation will not be accepted from the wireless remote controller that comes with the
room air conditioner. The operation partially enabled by the system controller can be operated with the wireless remote
controller. Regardless of whether the operation is disabled or enabled, 3 short beeps will sound when the signal is sent
from the wireless remote controller.
(4) Trouble
If the MA remote controller or the system controller shows the abnormal indication, clear it by stopping the operation with
one of the following: the MA remote controller, the system controller, or the wireless remote controller.
(Abnormal indication of the air conditioner could be recovered automatically, but that of the MA remote controller or the
system controller cannot be recovered unless the operation is stopped.)
IMPORTANT:
Make sure that the current leakage breaker
is one compatible with higher harmonics.
Always use a current leakage breaker that
is compatible with higher harmonics as this
unit is equipped with an inverter.
The use of an inadequate breaker can cause
the incorrect operation of inverter.
Longest length via outdoor units:
L1+ L2+ L3+ L4+ L5 ≤ 500 m (1640 ft) (1.25
mm² [AWG 16] or more)
Longest transmission cable length
L1+ L2, L3 + L4, L5 ≤ 200 m (656 ft) (1.25
mm² [AWG 16] or more)
OC: Outdoor unit
A-IC: A-control indoor unit
MA-RC: MA Remote controller
WL-RC:Wireless Remote controller

14
OCH801
(5) Group setting
MA group or M-NET group setting cannot be set.
(6) Restricted functions
The following functions of system controller cannot be used.
• DIDO controller (Interlock with the air conditioner)
• Fan control of energy saving control or peak cut control function
• Air conditioning charge [TG-2000A]
• Set temperature range limiting function
• Operation mode changeover limit (season changing) [PAC-SF44SRA]
• Dual set point function
• Setback mode
• Hold function
• MAC-333IF-E

15
OCH801
7 TROUBLESHOOTING
7-1. HOW TO CHECK THE PARTS
Parts name Checkpoint
Thermistor (TH-A–E)
<Gas pipe>
Disconnect the connector then measure the resistance with a multimeter.
(At the ambient temperature 50 to 86°F [10 to 30°C])
Thermistor R0=15kΩ ± 3%
Fixed number of B=3480 ± 2%
Rt=15exp { 3480 ( ) }
50F° [10°C] 9.7 kΩ
59F° [15°C] 7.9 kΩ
68F° [20°C] 6.4 kΩ
77F° [25°C] 5.3 kΩ
86F° [30°C] 4.4 kΩ
< Thermistor for lower temperature >
Temperature
Resistance (kΩ)
10
50 15 59 20 68 25 77 30°C 86°F
0
2
4
6
8
10
12
Linear expansion valve
( LEV-A–E ) Disconnect the connector then measure the resistance with a multimeter. (Winding temperature 68F° [20°C])
Normal Abnormal
Red - White Red - Orange Red - Yellow Red - Blue Open or short
46 ± 4Ω
1
273+t
1
273

16
OCH801
<Output pulse signal and the valve operation>
(2) Linear expansion valve operation
B
A
Open
Extra tightening (about 32 pulse)
Pulse number
500 pulse
Opening a valve
all the way
Close
Valve position (capacity)
Close
Open
The output pulse shifts in the following order.
Opening a valve: 8 → 7 → 6 → 5 → 4 → 3 → 2 → 1 → 8
Closing a valve: 1 → 2 → 3 → 4 → 5 → 6 → 7 → 8 → 1
• When linear expansion valve operation stops, all output phases
become OFF.
• When the power is turned on, 700 pulse closing valve signal will be
sent till it goes to point in order to define the valve position.
(The pulse signal is being sent for about 20 seconds.)
• When the valve moves smoothly, there is no sound or vibration
occurring from the linear expansion valve: however, when the pulse
number moves from to or when the valve is locked, sound can
be heard.
No sound is heard when the pulse number moves from to in
case coil is burnt out or motor is locked by open-phase.
• Sound can be detected by placing the ear against the screw driver
handle while putting the screw driver to the linear expansion valve.
Linear expansion valve
(1) Operation summary of the linear expansion valve
• Linear expansion valve opens/closes through stepping motor after receiving the pulse signal from the branch box controller
board.
• Valve position can be changed in proportion to the number of pulse signal.
<Connection between the branch box controller board and the linear expansion valve>
1
ON
OFF
OFF
OFF
ON
ON
OFF
OFF
OFF
ON
OFF
OFF
OFF
ON
ON
OFF
ø1
Output
(Phase)
Output
ø2
ø3
ø4
2 3 4 5 6 7 8
OFF
OFF
ON
OFF
OFF
OFF
ON
ON
OFF
OFF
OFF
ON
ON
OFF
OFF
ON
(LEV) in Branch box
LEV
M
1
5
ø4 ø
4
ø 3
ø 2
ø 1
1
Red
Blue
Orange
Yellow
White
2
3
4
5
Connector LEV-A
LEV-B
LEV-C
LEV-D
LEV-E
12 VDC
branch box controller board
Drive circuit
ø3
ø2
ø1
2
1
4
3

17
OCH801
Main body
Lead wire Stopper
Coil
(3) How to attach and detach the coil of linear expansion valve
<Composition>
Linear expansion valve is separable into the main body and the coil as shown in the diagram below.
A
<How to detach the coil>
Hold the lower part of the main body (shown as A) firmly so
that the main body does not move and detach the coil by
pulling it upward.
Be sure to detach the coil holding main body firmly.
Otherwise pipes can bend due to stress.
Be sure to attach the
stopper to pipe B.
BA
<How to attach the coil>
Hold the lower part of the main body (shown as A) firmly so that
the main body does not move and attach the coil by inserting it
downward into the main body. Then securely attach the coil stop-
per to pipe B. (At this time, be careful that stress is not added to
lead wire and main body is not wound by lead wire.) If the stopper
is not firmly attached to pipe B, coil may be detached from the
main body and that can cause defective operation of linear expan-
sion valve.
To prevent piping stress, be sure to attach the coil holding the
main body of linear expansion valve firmly. Otherwise pipe may
break.

18
OCH801
Troubleshooting
Problem Checkpoint Corrective measure
If the linear expansion valve becomes locked and the motor is still operating,
the motor will emit a clicking noise and will not function. This clicking noise
indicates an abnormality.
Use an all-purpose electrical meter to measure the resistance between the
different coils (red-white, red-orange, red-yellow, red-blue). Normal
resistance is within a range of 46 Ω ± 4 Ω/phase（at.20°C）.
In order to check the linear expansion valve, operate 1 indoor unit in the
fan mode and another in the cooling mode. Then, use the outdoor multi
controller board to operate the monitor and check the pipe temperature of
the indoor unit. The linear expansion valve should be fully closed when the
fan is operating. The temperature measured by the temperature sensor
will drop if there is any leakage.
If the measured temperature is significantly lower than that on the remote
controller, this indicates that the valve is not closed. It is not necessary to
replace the linear expansion valve if the leak of refrigerant is small and does
not cause a malfunction.
Check improperly connected connector terminals and the wire colors.
Remove the connector on the controller board side and check electrical
conductance.
Locked expansion
valve
Short circuit or broken
circuit in expansion
valve motor coil
Valve does not close
completely.
Incorrect connection
or connection failure
Replace the linear
expansion valve.
Replace the linear
expansion valve.
Replace the linear
expansion valve if there
is a major leak of
refrigerant.
Continuity check of
wrong part
①
②

19
OCH801
7-2. TEST POINT DIAGRAM
Branch box controller board (B.C.)
LEV-A to E
Connect to LEV-A to E
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
CND
Connected o the ter-
minal block (TB2B)
Power supply for
Branch box
Controller board
–208/230 VAC
F1
Fuse 6.3 A 250 V
F2,F3,F4
Fuse 10 A 250 V
F4 for PAC-MKA53BC
only
CN3M
Connected to the terminal
block (TB5)
(M-NET transmission con-
necting wire)
24–30 VDC (non polar)
TB3A to E
Connected to the indoor unit
S1-S2 (Power supply 208/230 VAC)
S3-S2 (Transmission 0–24 VDC)
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LEV-D and E for PAC-MKA53BC only
LED1,LED2
·Startup
Main power supply
(220/230 VAC)
·Normal operating
LED1: Main power supply
LED2: Blink depend on the
total number of indoor
units.
<Example>
The total number is 2.
Blink 2 times
Turn OFF for 3 seconds
Repeat –
TH-A to E
Connect to thermistor-A to E
TH-D and E for PAC-MKA53BC only
SW4
Mode selection
SW11
Address setting 1s DIGIT
SW12
Address setting 10s DIGIT
SW5
Service setting
SW1
Indoor unit connection
LED1: Main power supply
LED2: Blink depend on the
total number of indoor
Turn OFF for 3 seconds
LED1: Main power supply
LED2: Blink depend on the
total number of indoor
Turn OFF for 3 seconds
minal block (TB2B)
TB3D and TB3E is for PAC-
MKA53BC only

20
OCH801
7-3. INTERNAL SWITCH FUNCTION TABLE
Switch
Step
Function Operation in Each Switch Setting Remarks Additional Information
ON OFF When to Set
SW11
1s digit address setting SW12 10s digit address setting
Rotary switch
How to set addresses Example: if address is "3", remain SW12 (for over 10) at "0", and match SW11 (for 1 to 9) with "3".
Before turning
the power ON
<Initial settings>
10s digit
0
1
2
3
4
5
6
7
8
9
SW12
1s digit
0
1
2
3
4
5
6
7
8
9
SW11 —
SW1 Indoor unit connection
1–5
OFF ON
SW1
1Indoor unit A Not connected Connected 2 Indoor unit B Not connected Connected 3 Indoor unit C Not connected Connected 4*1Indoor unit D Not connected Connected
5*1Indoor unit E Not connected Connected
6Not used
Before turning
the power ON
<Initial settings>
1
ON
OFF
2 3 4 5 6
After each indoor unit is connected to the outdoor unit, turn ON the switch corresponding to each indoor unit. For example, when the indoor units are connected to INDOOR UNIT-A and C, turn SW1-1 and SW1-3 to ON.
SW4 Mode selection
1 — — — — <Initial settings>
—
2Power-supply voltage setting 230 V 208 V Set at factory only 3Change operation if M-NET
communication error occurs. Stop operation Continued
operation Before turning
the power ON
4Automatic restoration when the
power comes back ON.*2Inactive Active
5–8
— — — — — —
9
Detection of branch box pipe
thermistors No detection Detection Before turning
the power ON — —
0
— — — — ——
SW5 Service setting
1–3
Change INDOOR UNIT No. for
monitoring
Refer to "7-4. BRANCH
BOX UNIT OPERATION
MONITOR FUNCTION". Can be activated at
any time
<Initial settings>
—
The black square (■) indicates a switch position.
*1 Only for 5-branches model; NOT USED for 3-branches model. *2 Note that the automatic restoration starts after the unit has stopped once.
1
ON
OFF 2 3 4 5 6 7 8 9 0
1
ON
OFF 2 3 4 5 6 7 8 9 0