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Carrier 38AUZ Series - User Manual

Carrier 38AUZ Series
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38AUZD/E
Air Cooled Condensing Units, 60 Hz
Single Circuit, 2---Stage with Digital Scroll Compressor
and Puron
R
(R ---410A) Refrigerant
Size 08
Installation, Start---Up
and Service Instructions
TABLE OF CONTENTS
SAFETY CONSIDERATIONS 2....................
Rated Indoor Airflow (cfm) 3.....................
Matching 38AUZD/E08 Model to Evaporator Coil 6...
INSTALLATION 6--16...........................
Jobsite Survey 6................................
Step 1 -- Plan for Unit Location 6..................
Step 2 -- Complete Pre--Installation Checks 6.........
Step 3 -- Prepare Unit Mounting Support 6...........
Step 4 -- Rig and Mount the Unit 6.................
Step 5 -- Determine Refrigerant Line Sizes 7.........
Step 6 -- Complete Refrigerant Piping Connections 8....
Step 7 -- Install Accessories 10....................
Step 8 -- Complete Electrical Connections 10.........
Step 9 -- Wind Baffles for Low Ambient Controls 16...
PRE-START-UP 16...............................
System Check 16...............................
Turn On Crankcase Heater 16.....................
Preliminary Charge 16...........................
START--UP 16 -- 19..............................
Preliminary Checks 16...........................
Start Unit 17...................................
OPERATING SEQUENCE 20......................
Base Unit Controls 20...........................
Indoor (Supply) Fan 20..........................
Cooling, Unit Without Economizer 20..............
Cooling, Unit with Economizer 20.................
Heating 20....................................
ROUTINE SYSTEM MAINTENANCE 20............
Quar ter ly Insp ection (and 30 day s after initial start) 20...
Seasonal Maintenance 20........................
SERVICE 21 -- 27................................
Refrigeration System 21.........................
Compressor Oil 21..............................
Servicing Systems on Roofs with
Synthetic Materials 21...........................
Liquid Line Filter Drier 21.......................
Filed Refrigerant Access Ports 21..................
Factory High-- Flow Access Ports 21................
Comfort Alert Diagnosti c Module 22...............
Compressor Protection 24........................
Crankcase Heater 24............................
Low--Pressure Switch 24.........................
High--Pressure Switch 24.........................
Outdoor Fans 24................................
Lubrication 24.................................
Routine Cleaning of Round-Tube Plate Fin
(RTPF) Coils 26................................
Fastener Torque Values 27........................
TROUBLESHOOTING 27 -- 28.....................
APPENDIX A
Air Conditioner & Heat Pump with Puron
R
—
Quick Reference Guide 29.........................
APPENDIX B
Wiring Diagram List 29...........................
APPENDIX C
Low Ambient Option — Factory Installed 29..........
START--UP CHECKLIST 35 -- 36...................

Table of Contents

Questions and Answers

  • K
    Karen HarperAug 15, 2025
    What causes insufficient cooling when my Carrier Heat Pump compressor is running?
    • S
      susan59Aug 15, 2025
      If your Carrier Heat Pump's compressor is running but the cooling is insufficient, the issue could stem from low suction pressure (add refrigerant) due to a low refrigerant charge (add refrigerant). It may also be caused by low head pressure (check refrigerant charge and outdoor-air fan thermostat settings), dirty air filters (clean or replace them), a defective expansion valve power head (replace the power head), partially iced indoor coil (check low-pressure setting) or restricted indoor airflow (remove the obstruction). High suction pressure can also be the cause, so check for open doors or windows in the vicinity of the fan coil. Also, check for excessive heat load by looking for open doors or windows near the fan coil.
  • C
    Cynthia MartinezAug 18, 2025
    Why does my Carrier 38AUZ unit operate too long or continuously?
    • B
      Benjamin WoodAug 18, 2025
      If your Carrier Heat Pump operates for extended periods or continuously, it could be due to a low refrigerant charge (add refrigerant), fused control contacts (replace the control), air in the system (purge and evacuate the system), or a partially plugged expansion valve or filter drier (clean or replace).
  • S
    Susan Woods DDSAug 21, 2025
    What causes a frosted suction line in my Carrier 38AUZ Heat Pump?
    • M
      Mariah StevensAug 21, 2025
      A frosted suction line in your Carrier Heat Pump may be caused by the expansion valve admitting excess refrigerant. In this case, adjust the expansion valve.
  • A
    Abigail WuAug 25, 2025
    What causes a frosted liquid line on my Carrier Heat Pump?
    • L
      llawrenceAug 25, 2025
      A frosted liquid line on your Carrier Heat Pump may be caused by a restricted filter drier (remove the restriction or replace it) or a liquid line solenoid valve that is partially closed (replace the valve).
  • T
    Thomas MontoyaSep 5, 2025
    What to do if my Carrier Heat Pump system is noisy?
    • D
      dcastilloSep 5, 2025
      If your Carrier Heat Pump system is noisy, the cause might be piping vibration (support the piping as required) or a noisy compressor (replace the compressor if the bearings are worn).
  • B
    Bethany FlynnSep 8, 2025
    Why is the liquid line hot on my Carrier Heat Pump?
    • K
      Kevin PerezSep 8, 2025
      A hot liquid line in your Carrier Heat Pump can be caused by a shortage of refrigerant due to a leak (repair the leak and recharge) or an expansion valve that opens too wide (adjust the expansion valve).
  • B
    balexanderSep 12, 2025
    What to do if my Carrier 38AUZ compressor loses oil?
    • S
      Susan SmithSep 12, 2025
      If your Carrier Heat Pump compressor is losing oil, it could be due to a leak in the system (repair the leak), crankcase heaters not energized during shutdown (check wiring and relays, and replace the heater if defective), or an improper interconnecting piping design (check piping for oil return and replace if necessary).
  • L
    Lisa PayneNov 26, 2025
    What to do if my Carrier Heat Pump compressor does not run?
    • T
      Tina WaltonNov 26, 2025
      If your Carrier Heat Pump compressor isn't running, there are several potential causes. It could be due to an open contactor (restore power), blown fuses (replace with the correct size after fixing the cause), no control power (check control transformer connections and the circuit breaker), or an open thermostat circuit (check the thermostat setting). Other possible causes include an active safety device lockout circuit (reset it), an open low-pressure switch (check for refrigerant undercharge or airflow obstruction), or an open high-pressure switch (check for refrigerant overcharge, airflow obstruction, or air in the system). Also check for an open compressor overtemperature switch (allow for reset, replace if needed), loose electrical connections (tighten them), or a stuck compressor (re...
  • S
    Sharon HallDec 1, 2025
    Why does my Carrier 38AUZ Heat Pump compressor stop on high-pressure switch?
    • A
      Allen LunaDec 1, 2025
      Your Carrier Heat Pump compressor might stop due to the high-pressure switch being triggered. This could be due to a faulty high-pressure switch (replace it), reversed fan rotation (confirm and correct if needed), restricted airflow (remove the obstruction), air recirculating (clear the airflow area), noncondensables in the system (recover refrigerant and recharge), or refrigerant overcharge (recover refrigerant). Other possible causes include incorrect line voltage (consult the power company) or refrigerant system restrictions (check or replace the filter drier, expansion valve, etc.). The outdoor fan might not be functioning properly (tighten fan hub setscrews if the fan slips on the shaft, check power and capacitor if the motor isn't running, replace bearings if motor bearings are stuck...
  • S
    stevenhancockDec 3, 2025
    Why does my Carrier Heat Pump compressor cycle on low-pressure switch?

    Summary

    SAFETY CONSIDERATIONS

    Electrical Shock Hazard

    Warning about electrical shock during service operations.

    Unit Operation and Safety Hazards

    Warning regarding refrigerant pressure and R-22 components.

    Personal Injury and Environmental Hazards

    Warning on refrigerant handling, disposal, and safety.

    Cut Hazard

    Caution about sharp edges on sheet metal parts.

    INSTALLATION

    Jobsite Survey

    Pre-installation checks including codes and obstructions.

    Plan Unit Location

    Selecting location, clearances, and airflow considerations.

    Pre-Installation Checks

    Unit un-crating, shipment inspection, electrical checks.

    Prepare Mounting Support

    Installing concrete slab or support for the unit.

    Rig and Mount Unit

    Procedures for lifting and securing the unit.

    Determine Refrigerant Line Sizes

    Selecting appropriate refrigerant line sizes based on length.

    Complete Refrigerant Piping Connections

    Connecting refrigerant piping and ensuring safety.

    Install Liquid Line Solenoid Valve

    Recommends solenoid valve for migration prevention.

    Make Piping Connections

    Details connecting field tubing to unit service valves.

    Evacuation and Dehydration

    Procedures for evacuating the system to 500 microns.

    Install Accessories

    Installing optional accessories like winter start controls.

    Complete Electrical Connections

    Wiring unit according to NEC and local codes.

    Field Power Supply

    Connecting power supply to the unit's terminals.

    Factory-Installed Non-Fused Disconnect

    Installing the handle and shaft for NFD.

    Units Without Factory-Installed Disconnect

    Requirements for disconnect switch installation.

    Convenience Outlets

    Information on non-powered and unit-powered outlets.

    Unit-Powered Convenience Outlet

    Details on the unit-mounted transformer outlet.

    Field Control Wiring

    Thermostat Installation

    Installing and selecting a thermostat for the unit.

    CHECK VOLTAGE IMBALANCE

    PRE-START-UP

    System Checks

    Verifying electrical, air handler, and piping integrity.

    Crankcase Heater Activation

    Energizing crankcase heater for 24 hours before start.

    Preliminary Refrigerant Charge

    Adding initial refrigerant charge to the system.

    START-UP

    Compressor Overload Protection

    Information on compressor overload protection and reset.

    Advanced Scroll Temperature Protection (ASTP)

    Details on ASTP and its reset procedures.

    ROUTINE SYSTEM MAINTENANCE

    Quarterly Inspection

    Checks for indoor section components every 1-2 months.

    Seasonal Maintenance

    Checks for AC and heating components at season start.

    SERVICE

    Equipment Damage Hazard

    Warnings about using Puron refrigerant and correct equipment.

    Compressor Oil Handling

    Precautions for hygroscopic POE oil.

    Synthetic Roof Precautions

    Protecting roofing materials from oil exposure.

    Liquid Line Filter Drier

    Specifications and replacement of filter driers.

    Field Refrigerant Access Ports

    Location and use of access ports for service.

    Comfort Alert Diagnostic Module (CADM)

    Compressor Protection

    Crankcase Heater Operation

    Heater function and importance of continuous operation.

    Low and High-Pressure Switches

    Description and function of pressure switches.

    Outdoor Fan Assembly

    Adjusting fan height and motor lubrication.

    Compressor Lubrication

    Compressor oil supply and when to add oil.

    Coil Cleaning Procedures

    Totaline Coil Cleaner Application

    Equipment and steps for using environmentally sound cleaner.

    TROUBLESHOOTING

    Compressor Operation Issues

    Diagnosing issues like not running or stopping.

    System Performance Troubleshooting

    Diagnosing airflow, refrigerant, and electrical issues.

    APPENDIX A - Quick Reference Guide

    APPENDIX B - Wiring Diagram List

    APPENDIX C - Low Ambient Option

    START-UP CHECKLIST

    Carrier 38AUZ Series Specifications

    General IconGeneral
    BrandCarrier
    Model38AUZ Series
    CategoryHeat Pump
    LanguageEnglish

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