Mitsubishi Electric MUZ-WR12NA User Manual

Models
MUZ-WR09NA
-
U1
,
U2
MUZ-WR12NA
-
U1
,
U2
MUZ-WR18NA
-
U1
,
U2
MUZ-WR24NA
-
U1
HFC
utilized
R410A
MUZ-WR24NA
PARTS CATALOG (OBB819)
SERVICE MANUAL
No. OBH819
REVISED EDITION-B
Indoor unit service manual
MSZ-WR•NA Series (OBH818)
CONTENTS
1. TECHNICAL CHANGES ······························2
2. PART NAMES AND FUNCTIONS ··················3
3. SPECIFICATION ········································4
4. OUTLINES AND DIMENSIONS ·····················7
5. WIRING DIAGRAM ·····································9
6. REFRIGERANT SYSTEM DIAGRAM ··········· 12
7. DATA······················································ 15
8. ACTUATOR CONTROL ····························· 25
9. SERVICE FUNCTIONS ······························ 26
10. TROUBLESHOOTING ······························· 27
11. DISASSEMBLY INSTRUCTIONS ················· 52
OUTDOOR UNIT
OBH819 REVISED EDITION-A is void.
Revision B:
• MUZ-WR09/12/18NA-
U2
have been added.
• 10-4. The resistant value of the defrost
heater has been corrected.

Mitsubishi Electric MUZ-WR12NA Specifications

General

Category	Air Conditioner
Brand	Mitsubishi Electric
Model	MUZ-WR12NA
Refrigerant	R410A
Indoor Unit Dimensions (H x W x D)	11-5/8 x 33-1/8 x 9-1/8 inches
Outdoor Unit Dimensions (H x W x D)	21-5/8 x 31-1/2 x 11-13/16 inches
Cooling Capacity	12000 BTU/h
Power Supply	208/230V, 60Hz
Operating Temperature (Cooling)	14°F to 115°F

Summary

1 TECHNICAL CHANGES

3 SPECIFICATION

7 DATA

Performance Data

Presents cooling capacity and correction data for various models and conditions.

Performance Curves

Standard Operation Data

Table listing key operational data for different models under standard conditions.

Capacity and Input Correction by Inverter Frequency

8 ACTUATOR CONTROL

9 SERVICE FUNCTIONS

10 TROUBLESHOOTING

Troubleshooting Cautions

Important safety and procedural precautions before troubleshooting the unit.

Failure Mode Recall Function

Procedure for recalling and interpreting stored error codes from the unit.

Troubleshooting Flowcharts

Guides for diagnosing issues via systematic flowcharts and checks.

Check Inverter and Compressor

Flowchart for diagnosing inverter and compressor issues.

Check Open Phase

Check Compressor

Check Compressor Winding

Method to measure compressor winding resistance for defects.

Check Compressor Operation Time

Check Compressor Start Failure

Check Outdoor Thermistors

Check Reversing Valve Coil

Check Outdoor Fan Motor

Check Power Supply

Procedure to verify power supply and indicator status for troubleshooting.

Check Expansion Valve (LEV)

Check Inverter P.C. Board

Diagnostic steps for the inverter P.C. board, including LED indications.

Check Miswiring and Serial Signal Error

Troubleshooting guide for communication errors and wiring issues.

Check Defrost Heater

Check Outdoor Refrigerant Circuit

11 DISASSEMBLY INSTRUCTIONS

Disassembly MUZ-WR09/12/18NA Models

Disassembly MUZ-WR24NA Model