Carrier 38MGRBQ18B-3 Service Manual

38MG(R/H)B
Multi-zone Outdoor Unit Ductless System
Sizes 18R, 24HH, 30HH, 36R, 36HH, 48R and 48HH

TABLE of CONTENTS

SAFETY CONSIDERATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
MODEL / SERIAL NUMBER NOMENCLATURES . . . . . . . . . . . 2
CONNECTION DIAGRAMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
AUTOMATIC WIRING/PIPING CORRECTION . . . . . . . . . . . . . . 6
WIRING DIAGRAMS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
REFRIGERATION CYCLE DIAGRAMS . . . . . . . . . . . . . . . . . . . 15
REFRIGERANT LINES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
SYSTEM EVACUATION AND CHARGING . . . . . . . . . . . . . . . . 19
ELECTRONIC FUNCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
TROUBLESHOOTING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
OUTDOOR UNIT DIGITAL DISPLAY. . . . . . . . . . . . . . . . . . . . . 28
OUTDOOR UNIT DISPLAY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
DIAGNOSIS AND SOLUTION . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
APPENDICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
DISASSEMBLY INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . 81

SAFETY CONSIDERATIONS

Installing, starting up, and servicing air-conditioning equipment can
be hazardous due to system pressures, electrical components, and
equipment location (roofs, elevated structures, etc.).
Only trained, qualified installers and service mechanics should install,
start-up, and service this equipment. Untrained personnel can perform
basic maintenance functions such as coil cleaning. All other
operations should be performed by trained service personnel.
When working on the equipment, observe precautions in the literature
and on tags, stickers, and labels attached to the equipment.
Follow all safety codes. Wear safety glasses and work gloves. Keep a
quenching cloth and fire extinguisher nearby when brazing. Use care
in handling, rigging, and setting bulky equipment.
Read this manual thoroughly and follow all warnings or cautions
included in the literature and attached to the unit. Consult local
building codes and National Electrical Code (NEC) for special
requirements. Recognize safety information.
This is the safety-alert symbol
unit and in instructions or manuals, be alert to the potential for
personal injury. Understand these signal words: DANGER,
WARNING, and CAUTION.
SERVICE MANUAL
PAGE
. When you see this symbol on the
Specifications subject to change without notice.
These words are used with the safety-alert symbol. DANGER
identifies the most serious hazards which will result in severe personal
injury or death. WARNING signifies hazards which could result in
personal injury or death. CAUTION is used to identify unsafe
practices which may result in minor personal injury or product and
property damage. NOTE is used to highlight suggestions which will
result in enhanced installation, reliability, or operation.
WARNING
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury or death.
Before installing, modifying, or servicing system, main electrical
disconnect switch must be in the OFF position. There may be more
than 1 disconnect switch.
Lock out and tag switch with a suitable warning label.
WARNING
EXPLOSION HAZARD
Failure to follow this warning could result in
death, serious personal injury, and/or property
damage. Never use air or gases containing
oxygen for leak testing or operating refrigerant
compressors. Pressurized mixtures of air or
gases containing oxygen can lead to an
explosion.
CAUTION
EQUIPMENT DAMAGE HAZARD
Failure to follow this caution may result in equipment damage or
improper operation. Do not bury more than 36 in. (914 mm) of
refrigerant pipe in the ground. If any section of pipe is buried, there
must be a 6 in. (152 mm) vertical rise to the valve connections on the
outdoor units. If more than the recommended length is buried,
refrigerant may migrate to the cooler buried section during extended
periods of system shutdown. This causes refrigerant slugging and
could possibly damage the compressor at start-up.

INTRODUCTION

This service manual provides the necessary information to service,
repair, and maintain the multi-zone family of heat pumps. This
manual has an appendix with data required to perform
troubleshooting. see "APPENDICES" on page 73 Use the "TABLE of
CONTENTS" on page 1 to locate a desired topic.