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SPLIT-TYPE, HEAT PUMP AIR CONDITIONERS
TECHNICAL & SERVICE MANUAL
[Model Name]
<Branch box>
PAC-MKA33BC
PAC-MKA53BC
BRANCH BOX
[Service Ref.]
PAC-MKA33BC
PAC-MKA53BC
PAC-MKA53BC
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 (OCB801)
HFC
utilized
R410A
March 2023
No. OCH801
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-MKA53BC
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Page 1: Table Of Contents
PAC-MKA33BC describes technical data of PAC-MKA33BC branch box. As for indoor units and outdoor unit, refer to its service manual. PAC-MKA53BC PAC-MKA53BC CONTENTS 1. SAFETY PRECAUTION ··································· 2 2. OVERVIEW OF UNIT ······································ 5 3. SPECIFICATIONS ·········································· 8 4. OUTLINES AND DIMENSIONS ························· 9 5. -
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-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°...
- 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-MKA53BC PAC-MKA33BC Connectable number of indoor units Maximum 5 Maximum 3 Power supply Single phase, 208/230 V, 60 Hz Input 0.003 Running current 0.15 External finish Galvanized sheets 17-23/32 (450) Dimensions Width in (mm) Depth in (mm) -
Page 9: Outlines And Dimensions
〈1〉 TO OUTDOOR UNIT TO OUTDOOR UNIT CONDUIT PLATE SERV ICE PANEL 〈2-3/4〉 〈2-3/4〉 (for LEV, THERMISTOR) PAC-MKA53BC When installing the conduit. Set the attachment to the inner side of each panel. 58 〈2-9/32〉 SUSPENSION BOLT PITCH 〈25/32〉 〈1-3/32〉 320〈12-19/32〉... -
Page 10: Wiring Diagram
WIRING DIAGRAM OCH801... -
Page 11: Necessary Conditions For System Construction
NECESSARY CONDITIONS FOR SYSTEM CONSTRUCTION 6-1. TRANSMISSION SYSTEM SETUP OCH801... - Page 12 6-2. REFRIGERANT SYSTEM DIAGRAM ■ ■ PAC-MKA53BC PAC-MKA33BC 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 Outdoor unit TB3A TB5/TB15 Branch Box A-IC: A-control indoor unit A-IC MA-RC MA-RC: MA Remote controller (01) (51) WL-RC: Wireless Remote controller TB3B TB5/TB15 M1 M2 S M1 M2 S A-IC MA-RC (02) TB3C TB5/TB15 IMPORTANT: A-IC MA-RC Make sure that the current leakage breaker...
- Page 14 ( 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 •...
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Page 15: Troubleshooting
TROUBLESHOOTING 7-1. HOW TO CHECK THE PARTS Checkpoint Parts name Disconnect the connector then measure the resistance with a multimeter. Thermistor (TH-A–E) <Gas pipe> (At the ambient temperature 50 to 86°F [10 to 30°C]) Thermistor R0=15kΩ ± 3% < Thermistor for lower temperature > Fixed number of B=3480 ±... - 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 Corrective measure Problem 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 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-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...
- Page 20 7-3. INTERNAL SWITCH FUNCTION TABLE ■ The black square ( ) indicates a switch position. OCH801...
- 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, 2 3 4 5 6 (Direct-operated tens, and unit digit by turns.)
- Page 23 The black square (■) indicates a switch position. SW2 setting Unit Display detail Explanation for display SW5 setting* ― ― Common Not used −38 to 190 [−39 to 88] Individual unit Indoor thermistor <pipe temperature/ or less, "−" and temperature 2 3 4 5 6 °F (When the temperature is 0...
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Page 24: Disassembly Procedure
DISASSEMBLY PROCEDURE PHOTO: PAC-MKA53BC : Indicates the visible parts in the photos/figures. OPERATING PROCEDURE PHOTOS/FIGURES 1. Removing the controller cover and under panel Photo 1 (1) Remove 3 controller cover fixing screws (4 ᵡ 10) to detach Under panel fixing screws the controller cover. - Page 25 OPERATING PROCEDURE PHOTOS/FIGURES 3. Removing the LEV coil (LEV-A to E*) Photo 3 (1) Remove the controller cover. (See Photo 1) Rubber mount Bands Header assy (2) Remove the under cover. (See Photo 1) (3) Remove 8 insulations, then remove 9 pipe cover fixing LEV assy Bands screws (4 ᵡ...
- Page 26 OPERATING PROCEDURE PHOTOS/FIGURES 5. Removing the LEV assy Photo 5-1 (1) Remove the controller cover. (See Photo 1) LEV assy (2) Remove the under panel. (See Photo 1) (3) Remove 8 the insulations, then remove 9 pipe box (under) fixing screws (4 ᵡ 10). (See Photo 2-1) (4) Loosen the side clamps, then disconnect the LEV and thermistor connectors on the controller board.
- Page 27 OCH801...
- Page 28 HEAD OFFICE: TOKYO BUILDING, 2-7-3, MARUNOUCHI, CHIYODA-KU, TOKYO100-8310, JAPAN Copyright 2023 MITSUBISHI ELECTRIC CORPORATION Published: Mar. 2023 No.OCH801 Specifications are subject to change without notice. Made in Japan...