Mitsubishi Electric MUZ-WR18NA-U2 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-WR18NA-U2 Specifications

General

Heating Capacity	20, 000 BTU/h
Seasonal Energy Efficiency Ratio (SEER)	20.5
Power Supply	208/230V, 1-Phase, 60Hz
Refrigerant	R410A
HSPF	10.5
Voltage	208 / 230V
Operating Temperature (Cooling)	14°F to 115°F
Operating Temperature (Heating)	-13°F to 75°F

Summary

OUTDOOR UNIT SERVICE MANUAL

1 TECHNICAL CHANGES

3 SPECIFICATION

4 OUTLINES AND DIMENSIONS

5 WIRING DIAGRAM

6 REFRIGERANT SYSTEM DIAGRAM

MAX. REFRIGERANT PIPING LENGTH and MAX. HEIGHT DIFFERENCE

ADDITIONAL REFRIGERANT CHARGE (R410A: oz.)

Table and calculation for additional refrigerant charge based on piping length.

7 DATA

7-2. PERFORMANCE CURVE

7-3. CONDENSING PRESSURE

7-4. STANDARD OPERATION DATA

Standard operation data for capacity, input, and components.

7-5. CAPACITY AND INPUT CORRECTION BY INVERTER OUTPUT FREQUENCY

Correction factor graphs for capacity and input based on inverter frequency.

7-6. HOW TO OPERATE FIXED-FREQUENCY OPERATION (Test run operation)

Steps for performing a fixed-frequency test run operation.

8 ACTUATOR CONTROL

8-3. RELATION BETWEEN MAIN SENSOR AND ACTUATOR

9 SERVICE FUNCTIONS

10 TROUBLESHOOTING

10-1. CAUTIONS ON TROUBLESHOOTING

10-2. FAILURE MODE RECALL FUNCTION

Functionality and procedures for recalling stored failure modes.

10-3. TROUBLESHOOTING CHECK TABLE

Table listing common symptoms, LED indications, conditions, and remedies.

10-4. TROUBLE CRITERION OF MAIN PARTS

Criteria for checking main parts like thermistors, compressor, and motors.

10-5. TROUBLESHOOTING FLOW

Flowcharts for diagnosing various components and system issues.

10-6. TEST POINT DIAGRAM AND VOLTAGE

Diagrams showing test points and voltage readings on the inverter PC board.

11 DISASSEMBLY INSTRUCTIONS

11-1. MUZ-WR09NA MUZ-WR12NA MUZ-WR18NA

11-2. MUZ-WR24NA

2. Removing the inverter assembly, inverter P.C. board

Steps to remove the inverter assembly and PC board.

4. Removing the discharge temperature thermistor, defrost thermistor, outdoor heat exchanger temperature thermistor and ambient temperature thermistor

6. Removing the compressor and 4-way valve

Steps to remove the compressor and 4-way valve.