Mitsubishi Electric MU-18NN Series User Manual

SERVICE MANUAL
SPLIT-TYPE, AIR CONDITIONERS
CONTENTS
1. TECHNICAL CHANGES ····································2
2. PART NAMES AND FUNCTIONS······················3
3. SPECIFICATION·················································5
4. OUTLINES AND DIMENSIONS ·························7
5. WIRING DIAGRAM ············································8
6. REFRIGERANT SYSTEM DIAGRAM··············10
7. PERFORMANCE CURVES······························13
8. MICROPROCESSOR CONTROL ····················15
9. SERVICE FUNCTIONS ····································23
10. TROUBLESHOOTING······································24
11. DISASSEMBLY INSTRUCTIONS·····················30
12. PARTS LIST······················································34
13. OPTIONAL PARTS···········································38
Wireless type
Models
No. OB188
MS-18NN -
(
WH
)
· MU-18NN -
MS-24NN -
(
WH
)
· MU-24NN -
S1S1
S1S1
OB188--1.qxp 25/9/97 6:06 PM Page 3

Mitsubishi Electric MU-18NN Series Specifications

General

Brand	Mitsubishi Electric
Model	MU-18NN Series
Category	Air Conditioner
Language	English

Summary

Technical Changes

Part Names and Functions

Indoor Unit Components

Identifies and explains the components of the indoor unit.

Outdoor Unit Components

Identifies and explains the components of the outdoor unit.

Remote Controller Overview

Details the parts and functions of the remote controller.

Specifications

Outlines and Dimensions

Indoor Unit Dimensions

Presents physical dimensions and installation outlines for the indoor unit.

Outdoor Unit Dimensions

Presents physical dimensions and installation outlines for the outdoor unit.

Wiring Diagrams

Indoor Unit Wiring

Illustrates the electrical wiring connections for the indoor unit.

Outdoor Unit Wiring

Illustrates the electrical wiring connections for the outdoor unit.

Refrigerant System Diagram

MS-18NN / MU-18NN Refrigerant Flow

Shows the refrigerant flow and components for MS-18NN and MU-18NN models.

MS-24NN / MU-24NN Refrigerant Flow

Shows the refrigerant flow and components for MS-24NN and MU-24NN models.

Refrigerant Piping and Charge Specifications

Max Refrigerant Piping Length

Details maximum lengths and sizes for refrigerant piping.

Max Height Difference

Specifies the maximum allowable height difference between indoor and outdoor units.

Additional Refrigerant Charge

Provides guidelines for calculating additional refrigerant charge based on pipe length.

Evacuation Procedures

Performance Curves

Guaranteed Voltage and Air Flow

Specifies the acceptable voltage range and air flow setting for performance testing.

Main Readings for Performance Curves

Lists key temperature and input readings required for performance curve analysis.

Indoor Air Wet-Bulb Temperature Difference Measurement

Procedure to measure the wet-bulb temperature difference for performance evaluation.

Microprocessor Control

"I FEEL CONTROL" Operation Modes

Explains the "I FEEL CONTROL" mode and initial temperature-based operation.

Fuzzy and Temperature Control

Details how temperature buttons and fuzzy logic adjust settings for comfort.

Specific Operation Modes (COOL/DRY)

Describes the operational characteristics and frost prevention for COOL and DRY modes.

Fan, Vane, and Sleep Functions

Covers fan speed control, auto vane operation, and sleep mode functions.

Timer Operation

Setting and Cancelling Timers

Guides on setting, modifying, and cancelling ON/OFF timer operations.

Emergency and Test Operation

Service Functions

Timer Short Mode

Explains how to shorten timer settings for service purposes.

PC Board Modification for Multi-Unit Operation

Instructions for modifying PC boards to enable individual unit control.

Troubleshooting

Troubleshooting Precautions

Essential safety warnings and preliminary checks before troubleshooting.

Diagnostic Procedures and Criteria

Outlines diagnostic steps, check tables, component criteria, and procedures.

Diagnostic Flowcharts

Provides visual flowcharts to diagnose unit malfunctions systematically.

Test Point Diagrams

Illustrates test points and voltage measurements on the control PC board.

Disassembly Instructions

Indoor Unit Disassembly

Step-by-step guide for dismantling the indoor unit's components.

Outdoor Unit Disassembly

Step-by-step guide for dismantling the outdoor unit's components.

Parts List

Indoor Unit Structural Parts

Lists the structural components for the indoor unit with part numbers.

Indoor Unit Electrical Parts

Lists the electrical components for the indoor unit with part numbers.

Outdoor Unit Structural Parts

Lists the structural components for the outdoor unit with part numbers.

Indoor Unit Heat Exchanger & Accessory Parts

Lists heat exchanger and accessory parts for the indoor unit.

Optional Parts

Refrigerant Pipes

Details optional refrigerant pipes, lengths, and specifications.

Air Cleaning Filter

Information on the optional air cleaning filter, its function, and replacement.

Deodorizing Filter

Information on the optional deodorizing filter, its function, and cleaning.