Carrier 38MHRCQ24AA3 User Manual

Specifications subject to change without notice.
TABLE OF CONTENTS
PAGE
SAFETY CONSIDERATIONS ....................................................... 1
INTRODUCTION............................................................................ 1
MODEL / SERIAL NUMBER NOMENCLATURES .................... 2
SPECIFICATIONS (HEAT PUMP)................................................ 3
PERFORMANCE ............................................................................ 4
DIMENSIONS AND WEIGHTS .................................................... 5
CLEARANCES................................................................................ 9
ELECTRICAL DATA ..................................................................... 10
WIRING........................................................................................... 10
CONNECTION DIAGRAMS ......................................................... 11
WIRING DIAGRAMS (HEAT PUMP) .......................................... 12
REFRIGERATION CYCLE DIAGRAMS...................................... 15
SYSTEM EVACUATION AND CHARGING ............................... 20
TROUBLESHOOTING................................................................... 27
DIAGNOSIS AND SOLUTION...................................................... 31
DISASSEMBLY INSTRUCTIONS SIZES 9K (115V) - 18K (208/
230V)................................................................................................ 51
DISASSEMBLY INSTRUCTIONS SIZE 24K............................... 54
APPENDIX ...................................................................................... 57
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 . 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 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.
INTRODUCTION
This service manual provides the necessary information to service,
repair, and maintain the outdoor units. This manual has an appendix
with data required to perform troubleshooting. Use the “Table of
Contents” to locate a desired topic.
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.
WAR N I N G
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.
WAR N I N G
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.
CAUTION
Service Manual
38MHRC
Outdoor Unit Single Zone Ductless System
Sizes 09 to 24

Carrier 38MHRCQ24AA3 Specifications

General

Model Number	38MHRCQ24AA3
HSPF Rating	10.0
Voltage	208/230V
Phase	1
Refrigerant	R-410A
Compressor Type	Inverter
Stages	Variable
EER	12.5
Type	Heat Pump
Cooling Capacity	24000 BTU
Heating Capacity	27000 BTU
Indoor Unit Noise Level	19-44 dB
Outdoor Unit Noise Level	54 dB
Outdoor Unit Dimensions (HxWxD)	35.4 x 12.6 inches

Summary

SAFETY CONSIDERATIONS

General Safety Precautions

General safety guidelines for installing, starting, and servicing the equipment.

Electrical Shock Hazards

Warnings and precautions regarding electrical shock hazards during service.

Explosion Hazard Warning

Warning about explosion risk when using oxygen or air mixtures with refrigerants.

Equipment Damage Hazard

Caution regarding burying refrigerant pipes and potential damage.

MODEL / SERIAL NUMBER NOMENCLATURES

Unit Size and Model Identification

Explains the structure of the model and serial number nomenclature for unit identification.

SPECIFICATIONS (HEAT PUMP)

Electrical and Operating Specifications

Details electrical data, operating ranges, and piping specifications for heat pump units.

PERFORMANCE

Cooling and Heating Performance Data

Provides performance metrics like capacity, SEER, EER, HSPF, and COP for various models.

DIMENSIONS AND WEIGHTS

Unit Dimensions and Weight

Presents physical dimensions, weights, and packaging details for different unit sizes.

CLEARANCES

Required Installation Clearances

Specifies minimum clearance requirements for unit installation and airflow.

ELECTRICAL DATA

Power Supply and Compressor Electricals

Details electrical specifications for power supply, compressor, and outdoor fan motor.

Wiring Connection Method

Recommended connection methods for power and communication wiring, including EMF considerations.

CONNECTION DIAGRAMS

Wiring Diagrams for 115V and 208-230V Units

Illustrates electrical connections between indoor and outdoor units for different voltage systems.

WIRING DIAGRAMS (HEAT PUMP)

Wiring Diagram for 12K (115V) Unit

Provides a detailed wiring diagram for the 12K 115V heat pump unit.

WIRING DIAGRAMS (CONT)

Wiring Diagram for 9-18K (208-230V) Units

Shows the wiring diagram for 9-18K units operating on 208-230V.

WIRING DIAGRAMS (CONT)

Wiring Diagram for 24K (208-230V) Unit

Presents the wiring diagram for the 24K 208-230V unit.

REFRIGERATION CYCLE DIAGRAMS

Refrigerant Flow Diagram for 12K Units

Illustrates the refrigerant flow path for 12K units in cooling and heating modes.

REFRIGERATION CYCLE DIAGRAMS (CONT)

Refrigerant Flow Diagram for 9K Unit

Details the refrigerant cycle and flow for the 9K 208/230V unit.

REFRIGERATION CYCLE DIAGRAMS (CONT)

Refrigerant Flow Diagram for 18K Unit

Shows the refrigeration cycle and flow for the 18K 208/230V unit.

REFRIGERATION CYCLE DIAGRAMS (CONT)

Refrigerant Flow Diagram for 24K Unit

Illustrates the refrigerant cycle and flow for the 24K 208/230V unit.

REFRIGERANT LINES

General Refrigerant Line Sizing and Charge

Guidelines for sizing refrigerant lines, insulation, and charge adjustments.

Long-Line Applications

Specific instructions for line sizing and refrigerant addition in long-line applications.

SYSTEM EVACUATION AND CHARGING

Deep Vacuum Method

Procedure for achieving a deep vacuum to remove moisture and contaminants.

Triple Evacuation Method

Step-by-step guide for the triple evacuation process using dry nitrogen.

Final Tubing Check

Important checks for tubing integrity and security before system operation.

ELECTRONIC FUNCTIONS

Main Protection Functions

Details on compressor restart delay, high temp cutout, fan speed control, and inverter protection.

Operation Modes and Functions

Explains FAN mode, COOLING mode rules, and outdoor fan speed control based on ambient temp.

ELECTRONIC FUNCTIONS (CONT)

Indoor Fan Running Rules

Describes indoor fan speed control in cooling and auto modes based on temperature differentials.

Compressor Temperature Protection

Details compressor protection mechanisms based on temperature thresholds.

HEATING Mode Operations

Covers compressor and outdoor fan running rules during heating operations.

ELECTRONIC FUNCTIONS (CONT)

Indoor Fan Running Rules (Heating)

Explains indoor fan control during heating, including anti-cold air function.

Auto Fan in HEATING Mode

Details auto fan operation logic during heating mode based on temperature.

DEFROST Mode

Defrost Operation and Control

Explains how the unit enters defrost mode based on temperature and running time.

Forced DEFROSTING Mode Entry

Procedure to manually enter and exit the forced defrosting mode.

Defrost Exit Conditions

Lists the conditions that will cancel the defrost mode and resume normal heating.

ELECTRONIC FUNCTIONS (CONT)

Evaporator Coil Temperature Protection

How evaporator temperature impacts compressor operation and protection.

AUTO Mode Operation

Describes the unit's behavior and selection of modes in AUTO mode.

DRYING Mode and Protections

Details operation and protections specific to the DRYING mode.

Forced OPERATION Function

How to engage and use forced operation modes like AUTO and COOLING.

Refrigerant Leakage Detection

Functionality and display for detecting refrigerant leaks.

POINT CHECK FUNCTION

Enquiry Information Display

How to access and interpret diagnostic codes and sensor readings via the remote.

TROUBLESHOOTING

Safety Precautions for Troubleshooting

Crucial safety warning about discharging capacitors before handling.

Outdoor Unit Diagnostic Guide

Error Code Identification

Lists operation lamp and timer lamp patterns corresponding to specific error codes.

PCB DIAGRAMS

12K (115V) PCB Layout

Illustrates the component layout and connections on the 12K 115V PCB.

PCB DIAGRAMS (CONT)

LED Error Code Indicators

Explains the meaning of LED flashes and combinations for troubleshooting.

DIAGNOSIS AND SOLUTION

EEPROM Parameter Error (E0/F4)

Describes the cause, possible issues, and troubleshooting steps for EEPROM errors.

Indoor/Outdoor Unit Communication Error (E1)

Troubleshooting guide for communication errors between indoor and outdoor units.

Testing DC Voltage and Reactor Resistance

Procedures for testing DC voltage and reactor resistance using a multimeter.

Zero Crossing Detection Error (E2)

Diagnosis and solution for errors related to abnormal zero crossing signal intervals.

Indoor Fan Speed Out of Range (E3/F5)

Troubleshooting steps for issues with indoor fan speed being too slow or too fast.

Fan Motor Connector and Voltage Checks

Details on checking DC motor voltage inputs/outputs and AC fan motor voltage.

Temperature Sensor Circuit Errors (E4/E5/F1/F2/F3)

Troubleshooting open or short circuits in temperature sensors.

Refrigerant Leakage Detection (EC)

Diagnosis and solution for refrigerant leakage detection errors.

Overload Current Protection (F0)

Troubleshooting steps for overload current protection issues.

IPM/IGBT Over-Current Protection (P0)

Diagnosis and solution for IPM or IGBT over-current protection faults.

Testing IPM Output Voltages P-U, P-V

Procedures for testing specific voltage outputs from the IPM module.

Testing IPM Output Voltages P-W, N-U

Procedures for testing specific voltage outputs from the IPM module.

Testing IPM Output Voltages N-V, N-W

Procedures for testing specific voltage outputs from the IPM module.

Over Voltage/Low Voltage Protection (P1)

Diagnosis and solution for over or under voltage protection issues.

Compressor Top Temperature Protection (P2)

Troubleshooting for high temperature protection of the compressor top.

Inverter Compressor Drive Error (P4)

Diagnosis and solution for abnormal inverter compressor drive errors.

Main Parts Check Procedures

General guidance for checking temperature sensors and other key components.

Compressor Resistance Checking

Method for checking compressor winding resistance values.

IPM Continuity and Fan Motor Resistance

Procedures for IPM continuity checks and fan motor resistance measurements.

Pressure on the Service Port

Cooling Pressure/Temperature Chart

Provides pressure readings for various temperature conditions during cooling.

Pressure on the Service Port (Cont)

Heating Pressure/Temperature Chart

Provides pressure readings for various temperature conditions during heating.

DISASSEMBLY INSTRUCTIONS SIZES 9K (115V) - 18K (208/230V)

Disassembly Procedure for 9K-18K Units

Step-by-step instructions for disassembling outdoor units of 9K and 18K sizes.

DISASSEMBLY INSTRUCTIONS SIZE 24K

Disassembly Procedure for 24K Unit

Step-by-step instructions for disassembling the 24K outdoor unit.

APPENDIX

Temperature Sensor Resistance Tables

Tables providing resistance values for temperature sensors at various temperatures.