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SPLIT-TYPE, HEAT PUMP AIR CONDITIONERS
TECHNICAL & SERVICE MANUAL
[Model Name]
<Branch box>
PAC-MK54BC
PAC-MK34BC
BRANCH BOX
[Service Ref.]
PAC-MK54BC
PAC-MK34BC
PAC-MK54BC
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
PARTS CATALOG (OCB744)
HFC
utilized
R410A
May 2020
No. OCH744
Note:
• This service manual
describes technical data of
branch box. As for indoor
units and outdoor unit,
refer to its service manual.
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Summary of Contents for Mitsubishi Electric PAC-MK54BC
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Page 1: Table Of Contents
May 2020 No. OCH744 TECHNICAL & SERVICE MANUAL [Model Name] [Service Ref.] Note: <Branch box> • This service manual PAC-MK54BC describes technical data of PAC-MK54BC branch box. As for indoor units and outdoor unit, refer to its service manual. PAC-MK34BC PAC-MK34BC CONTENTS 1. -
Page 2: Safety Precaution
SAFETY PRECAUTION 1-1. CAUTIONS RELATED TO NEW REFRIGERANT Cautions for units utilizing refrigerant R410A Precautions during the repair service Preparation before the repair service • Do not perform the work involving the electric parts • Prepare the proper tools. with wet hands. •... - Page 3 [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. [2] Additional refrigerant charge When charging directly from cylinder (1) Check that cylinder for R410A on the market is a syphon type.
- Page 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.
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Page 5: Overview Of Unit
OVERVIEW OF UNIT 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. - Page 6 2-2. INSTALLATION Space required for Installation and servicing for branch box for PAC-MK54/34BC (1) Front View (Fig. 2-1) A Branch box B On the side of piping (2) Side View (Fig. 2-2, Fig. 2-3, Fig. 2-4) C For indoor installations D Ceiling board E Maintenance hole F Reactor box (Optional parts) *1: A minimum 350 mm is required for 90°...
- Page 7 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.
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Page 8: Specifications
SPECIFICATIONS Model Name PAC-MK54BC PAC-MK34BC Connectable number of indoor units Maximum 5 Maximum 3 Power supply (from outdoor unit) ~/N, 220/230/240 V, 50 Hz, ~/N, 220/230 V, 60 Hz Input 0.003 Running current 0.05 (Max. 6) External finish Galvanized sheets... -
Page 9: Outlines And Dimensions
OUTLINES AND DIMENSIONS Unit: mm PAC-MK54BC SUSPENSION BOLT PITCH SUSPENSION BOLT : W3/8(M10) REFRIGERANT PIPE FLARED CONNECTION TO OUTDOOR UNIT { 6.35 { 6.35 { 6.35 { 6.35 { 6.35 { 9.52 LIQUID PIPE GAS PIPE { 9.52 { 9.52 { 9.52... -
Page 10: Wiring Diagram
2 Turn off for 3 sec. LEV-A~E Linear expansion valve 3 Repeat 1 to 2 . TH-A~E Thermistor <Gas pipe> 6 D and E for PAC-MK54BC only TB2B Terminal block <To Power Supply> Transmission line REACTOR BOX Optional parts <Note>... -
Page 11: Necessary Conditions For System Construction
NECESSARY CONDITIONS FOR SYSTEM CONSTRUCTION 6-1. TRANSMISSION SYSTEM SETUP OCH744... - Page 12 6-2. REFRIGERANT SYSTEM DIAGRAM ■ ■ PAC-MK54BC PAC-MK34BC Thermistor (TH-A–E) Thermistor (TH-A–C) (Gas pipe temperature) (Gas pipe temperature) LEV A–E LEV A–C (Linear expansion valve) (Linear expansion valve) Strainer Strainer #100 #100 Strainer Strainer #100 #100 Capillary Capillary tube tube...
- Page 13 6-3. TYPICAL CONTROL SYSTEM Branch Box TB3A TB5/TB15 Outdoor unit A-IC MA-RC (01) M-IC: M-NET Control indoor unit (CITY MULTI indoor unit) (51) A-IC: A-control indoor unit TB3B TB5/TB15 M1 M2 S M1 M2 S A-IC MA-RC: MA Remote controller MA-RC (02) WL-RC: Wireless Remote controller...
- Page 14 ( 5) Group setting 1 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 •...
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Page 15: Troubleshooting
TROUBLESHOOTING 7-1. HOW TO CHECK THE PARTS BRANCH BOX: PAC-MK54BC PAC-MK34BC Parts name Checkpoint Thermistor (TH-A–E) Disconnect the connector then measure the resistance with a tester. <Gas pipe> (At the ambient temperature 10 to 30°C) Thermistor R0=15k" ± 3% < Thermistor for lower temperature >... - Page 16 Linear expansion valve (LEV) in Branch box (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>...
- Page 17 (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. Main body Coil Lead wire Stopper <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.
- Page 18 Troubleshooting Checkpoint Problem Corrective measure Locked expansion Replace the linear If the linear expansion valve becomes locked and the motor is still operating, valve expansion valve. the motor will emit a clicking noise and will not function. This clicking noise indicates an abnormality.
- Page 19 PAC-MK54BC PAC-MK34BC LEV-A to E TH-A to E Connect to LEV-A to E Connect to thermistor-A to E LEV-D and E for PAC-MK54BC only TH-D and E for PAC-MK54BC only CN3M Connected to the terminal block (TB5) (M-NET transmission con- necting wire) 24–30 VDC (non polar)
- Page 20 7-3. INTERNAL SWITCH FUNCTION TABLE ■ The black square ( ) indicates a switch position. OCH744...
- Page 21 7-4. BRANCH BOX UNIT OPERATION MONITOR FUNCTION [When optional part ‘A-Control Service Tool (PAC-SK52ST)’ is connected to branch box controller board (CNM)] Digital indicator LED1 displays 2 digit number or code to inform operation condition and the meaning of check code by controlling DIP SW2 on ‘A-Control Service Tool’.
- Page 22 The black square (■) indicates a switch position. SW2 setting SW5 setting* Display detail Explanation for display Unit ― ― Common Not used Individual unit Actual opening pulse 0 to 500 of LEV (When it is 100 pulse or more, it displays a hundredth, (Direct-operated tens, and unit digit by turns.) conversion value)
- Page 23 The black square (■) indicates a switch position. SW2 setting Display detail Explanation for display Unit SW5 setting* ― ― Common Not used Individual unit Indoor thermistor −39 to 88 <pipe temperature/ (When the temperature is 0°C or less, "−" and temperature 2 3 4 5 6 2-phase>...
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Page 24: Disassembly Procedure
DISASSEMBLY PROCEDURE BRANCH BOX: PAC-MK54BC PAC-MK34BC PHOTO: PAC-MK54BC OPERATING PROCEDURE PHOTOS/FIGURES Photo 1 1. Removing the controller cover and under panel (1) Remove 3 controller cover fixing screws (4 o 10) to Under panel fixing screws detach the controller cover. (See Photo 1) (2) Remove 4 under panel fixing screws (4 o 10) to remove the under panel. - Page 25 OPERATING PROCEDURE PHOTOS/FIGURES Photo 3 3. Removing the LEV coil (LEV-A–E*) (1) Remove the controller cover. (See Photo 1) Bands (2) Remove the under cover. (See Photo 1) (3) Remove 8 insulations, then remove 9 pipe cover fixing Header assy screws (4 x 10).
- Page 26 OPERATING PROCEDURE PHOTOS/FIGURES Photo 5-1 5. Removing the LEV assy LEV assy (1) Remove the controller cover. (See Photo 1) (2) Remove the under panel. (See Photo 1) (3) Remove 8 the insulations, then remove 9 pipe cover fix- ing screws (4 x 10). (See Photo 2-1) (4) Loosen the side clamps, then disconnect the LEV con- nectors on the controller board.
- Page 27 OCH744...
- Page 28 HEAD OFFICE: TOKYO BUILDING, 2-7-3, MARUNOUCHI, CHIYODA-KU, TOKYO100-8310, JAPAN cCopyright 2020 MITSUBISHI ELECTRIC CORPORATION Published: May 2020 No.OCH744 Made in Japan Specifications are subject to change without notice.