Mitsubishi Electric MUZ-FH18NAH2 User Manual

SERVICE MANUAL
Models
OUTDOOR UNIT
Indoor unit service manual
MSZ-FH•NA Series (OBH683)
NOTE:
RoHS compliant products have <G> mark on the spec name plate.
HFC
utilized
R410A
No. OBH684
REVISED EDITION-C
PARTS CATALOG (OBB684)
MUZ-FH06NA
MUZ-FH09NA
MUZ-FH12NA
MUZ-FH06NAH
MUZ-FH09NAH
MUZ-FH12NAH
Please void OBH684 REVISED EDITION-B.
Revision C:
• MUZ-FH06NA, MUZ-FH09/12NA-
1
, MUZ-
FH18NA2, MUZ-FH06NAH, MUZ-
FH09/12NAH-
1
and MUZ-FH18NAH2
have been added.
MUZ-FH06NA
MUZ-FH09NA
MUZ-FH09NA
-
1
MUZ-FH12NA
MUZ-FH12NA
-
1
MUZ-FH15NA
MUZ-FH18NA
MUZ-FH18NA2
MUZ-FH06NAH
MUZ-FH09NAH
MUZ-FH09NAH
-
1
MUZ-FH12NAH
MUZ-FH12NAH
-
1
MUZ-FH15NAH
MUZ-FH18NAH
MUZ-FH18NAH2
CONTENTS
1. TECHNICAL CHANGES ······························2
2. PART NAMES AND FUNCTIONS ··················3
3. SPECIFICATION ········································4
4. OUTLINES AND DIMENSIONS ·····················6
5. WIRING DIAGRAM ·····································8
6. REFRIGERANT SYSTEM DIAGRAM ··········· 14
7. DATA······················································ 16
8. ACTUATOR CONTROL ····························· 27
9. SERVICE FUNCTIONS ······························ 28
10. TROUBLESHOOTING ······························· 29
11. DISASSEMBLY INSTRUCTIONS ················· 51

Mitsubishi Electric MUZ-FH18NAH2 Specifications

General

Type	Heat Pump
Cooling Capacity	18, 000 BTU/h
Heating Capacity	21, 600 BTU/h
Seasonal Energy Efficiency Ratio (SEER)	20.5
Refrigerant	R-410A
Voltage	208/230V
Operating Temperature (Cooling)	14°F to 115°F
Operating Temperature (Heating)	-13°F to 75°F
Power Supply	1 Phase, 60 Hz
Sound Level (dB)	49 dB

Summary

Technical Changes

New Models Added

Lists newly added outdoor unit models to the service manual.

Data

7-1. Performance Data

Troubleshooting

10-1. Cautions on Troubleshooting

Important safety precautions and initial checks before troubleshooting.

10-2. Failure Mode Recall Function

Procedure to recall memorized failure modes for diagnosis.

2. Flow chart of the detailed outdoor unit failure mode recall function

3. Outdoor unit failure mode table

10-3. Troubleshooting Check Table

10-4. Trouble Criterion of Main Parts

Specifies resistance and voltage criteria for checking major components.

A How to check inverter/compressor

Step-by-step guide to check the inverter and compressor for faults.

B Check of open phase

Procedure to check for open phase issues in the inverter output.

D Check of compressor winding

Method to measure compressor winding resistance to identify shorts or opens.

E Check of compressor operation time

F Check of compressor start failure

Steps to diagnose and resolve compressor start-up failures.

G Check of outdoor thermistors

Instructions for checking the resistance of various outdoor thermistors.

H Check of R.V. coil

① Check of outdoor fan motor

J Check of power supply

K Check of LEV (Expansion valve)

Check of inverter P.C. board

Procedures to diagnose issues with the inverter P.C. board, including fuse and LED checks.

M How to check miswiring and serial signal error

Guide to identify and resolve miswiring and serial communication errors.

N Check of defrost heater

Check of outdoor refrigerant circuit

Disassembly Instructions

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

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

5. Removing outdoor fan motor

6. Removing the compressor and 4-way valve

Detailed procedure for removing the compressor and 4-way valve for FH15/FH18 models.