Mitsubishi Electric PAC-AK50BC Operating manual

TECHNICAL & SERVICE MANUAL
SPLIT-TYPE, HEAT PUMP AIR CONDITIONERS
CONTENTS
1. SAFETY PRECAUTION ······································· 2
2. OVERVIEW OF UNIT ··········································· 5
3. SPECIFICATIONS ················································ 8
4. OUTLINES AND DIMENSIONS ··························· 9
5. WIRING DIAGRAM ············································· 10
6. REFRIGERANT SYSTEM DIAGRAM ················· 11
7. TROUBLESHOOTING ········································ 12
8. DISASSEMBLY PROCEDURE ··························· 23
BRANCH BOX
No. OCH508
REVISED EDITION-A
HFC
utilized
R410A
April 2013
NOTE:
• This service manual
describes technical data of
branch box. As for indoor
units and outdoor unit,
refer to its service manual.
PARTS CATALOG (OCB508)
[Service Ref.]
PAC-AK50BC
PAC-AK51BC
PAC-AK52BC
PAC-AK53BC
PAC-AK30BC
PAC-AK31BC
PAC-AK32BC
Revision:
• PAC-AK53BC and PAC-
AK32BC have been added
in REVISED EDITION-A.
• Some descriptions have
been modified.
• Please void OCH508.
[Model name]
<Branch box>
PAC-AK50BC
PAC-AK51BC
PAC-AK52BC
PAC-AK53BC
PAC-AK30BC
PAC-AK31BC
PAC-AK32BC
(Indispensable optional parts for MXZ-8A series and MXZ-8B series. )

2
1 SAFETY PRECAUTION
Cautions for units utilizing refrigerant R410A
1-1. ALWAYS OBSERVE FOR SAFETY
Use new refrigerant pipes.
Charge refrigerant from liquid phase of gas
cylinder.
If the refrigerant is charged from gas phase, composition
change may occur in refrigerant and the efficiency 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.
Use a vacuum pump with a reverse flow check
valve.
Vacuum pump oil may flow back into refrigerant cycle and
that can cause deterioration of refrigerant oil etc.
Use the following tools specifically designed for
use with R410A refrigerant.
The following tools are necessary to use R410A refrigerant.
Handle tools with care.
If dirt, dust or moisture enters into refrigerant cycle, that can
cause deterioration of refrigerant oil or malfunction of com-
pressor.
Do not use a charging cylinder.
If a charging cylinder is used, the composition of refrigera-
nt will change and the efficiency will be lowered.
Flare tool
Electronic refrigerant
charging scale
Vacuum pump adaptor
Size adjustment gauge
Gauge manifold
Torque wrench
Gas leak detector
Charge hose
Tools for R410A
Contamination inside refrigerant piping can cause deterio-
ration of refrigerant oil etc.
If dirt, dust or moisture enters into refrigerant cycle, that can
cause deterioration of refrigerant oil or malfunction of com-
pressor.
If large amount of mineral oil enters, that can cause deterio-
ration of refrigerant oil etc.
Store the piping indoors, and both ends of the
piping sealed until just before brazing.
(Leave elbow joints, etc. in their packaging.)
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 specified thickness.
The refrigerant oil applied to flare and flange
connections must be ester oil, ether oil or
alkylbenzene oil in a smalll amount.
Never use any refrigerant other than that specified.
Doing so may cause a burst, an explosion, or fire when the
unit is being used, serviced, or disposed of.
Correct refrigerant is specified 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.
Use the specified refrigerant only. Ventilate the room if refrigerant leaks during
operation. If refrigerant comes into contact with
a flame, poisonous gases will be released.
1-2. CAUTIONS RELATED TO NEW REFRIGERANT
Before obtaining access to terminal, all supply
circuit must be disconnected.
OCH508A

3
Gravimeter
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
· Check that cylinder for R410A on the market is syphon type.
· 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) When performing service, install a filter drier simultaneously.
Be sure to use a filter drier for new refrigerant.
No. Tool name Specifications
1Gauge manifold
· Only for R410A
· Use the existing fitting specifications. (UNF1/2)
· Use high-tension side pressure of 5.3MPa·G or over.
2Charge hose · Only for R410A
· Use pressure performance of 5.09MPa·G or over.
3Electronic scale
4Gas leak detector · Use the detector for R134a, R407C or R410A.
5Adaptor for reverse flow check · Attach on vacuum pump.
6Refrigerant charge base
7Refrigerant cylinder · Only for R410A · Top of cylinder (Pink)
· Cylinder with syphon
8Refrigerant recovery equipment
OCH508A

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.
1 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.)
2 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 of its working pressure higher than that of other refriger-
ants. Therefore, to enhance airtightness and intensity, 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 intensity as shown below. Set copper pipe correctly referring to copper pipe flaring
dimensions for R410A below. For 1/2” and 5/8”, the dimension B changes.
Use torque wrench corresponding to each dimension.
3 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
6.35
9.52
12.70
15.88
19.05
0.8
0.8
0.8
1.0
—
0.8
0.8
0.8
1.0
1.0
Nominal
dimensions(inch)
Diagram below: Piping diameter and thickness
Outside
diameter (mm)
Thickness (mm)
R410A R22
1/4
3/8
1/2
5/8
3/4
6.35
9.52
12.70
15.88
19.05
9.1
13.2
16.6
19.7
—
9.0
13.0
16.2
19.4
23.3
Nominal
dimensions(inch)
Flare cutting dimensions
Outside
diameter
Dimension A ( )
+0
-0.4
(mm)
R410A R22
1/4
3/8
1/2
5/8
3/4
6.35
9.52
12.70
15.88
19.05
17.0
22.0
26.0
29.0
—
17.0
22.0
24.0
27.0
36.0
Nominal
dimensions(inch)
Flare nut dimensions
Outside
diameter
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
OCH508A

5
2 OVERVIEW 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 realizes a long distance piping for big houses. Equipped with a microprocessor, the Branch Box can trans-
late the transmission signal of indoor units to achieve the optimum control.
2-1-1. System example
2-1-2. Method for identifying
■ Outdoor unit
M X Z – 8 B 140 V A
Model type
Power supply
V: Single phase 220/230/240V 50Hz
Y: 3-Phase 380/400/450V 50Hz
Multi type heat pump
inverter outdoor unit
Indicates equivalent to rated cooling capacity.
(0.1kW)
Number of connectable indoor units (MAX.)
Control and refrigerant
A : New A control and R410A
Branch box (Controller)
Number of branches
5 : 5 branches
3 : 3 branches
Model type
Symbol of factory
Applicable refrigerant
A : R410A
P A C – A K 5 2 BC
(Indispensable)
Optional parts
■ Branch box
OCH508A