Carrier 40MUAAQ18XB3 Service Manual

40MUAA
Air Handler Unit
Sizes 18 to 60

TABLE OF CONTENTS

SAFETY CONSIDERATIONS ....................................................... 1
INTRODUCTION............................................................................ 1
MODEL NUMBER NOMENCLATURE ....................................... 2
AUXILLIARY CONTACTS FOUND ON THE MAIN BOARD .. 3
ROTARY AND DIP SWITCHES ................................................... 6
INDOOR UNIT WIRING................................................................ 8
WIRING REQUIREMENTS ........................................................... 9
CONNECTION DIAGRAMS ......................................................... 10
WIRING DIAGRAMS..................................................................... 11
REFRIGERANT LINES .................................................................. 12
TROUBLESHOOTING................................................................... 13
DIAGNOSIS AND SOLUTION...................................................... 16
DISASSEMBLY INSTRUCTIONS ................................................ 35
APPENDICES.................................................................................. 41

SAFETY CONSIDERATIONS

Installing, starting up, and servicing air-conditioning equipment can
be hazardous due to unit 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 only.
When working on the equipment, observe the 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 the warnings or cautions
included in the literature and attached to the unit. Consult local building
codes and the National Electrical Code (NEC) for special requirements.
Recognize safety information. This is the safety-alert symbol
When you see this symbol on the unit and in instructions or manuals,
be alert to the potential for personal injury. Understand these signal
words: DANGER, WARNING, and CAUTION.
These words are used with the safety-alert symbol. DANGER
identifies the most serious of 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.
Service Manual
PAGE
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury or
death. Before installing, modifying, or servicing the unit, the
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.
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 the extended periods
of unit 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 indoor units. This manual contains an
"DISASSEMBLY INSTRUCTIONS" on page 35 with data required to
troubleshoot issues. Use the "TABLE OF CONTENTS" on page 1 to
locate a desired topic.
Specifications subject to change without notice.
WARNING
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