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McQuay ACZ 028A - User Manual

McQuay ACZ 028A
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Installation, Operation and Maintenance Manual
IOMM ACZ1
Group:
Chiller
Part Number
: 330262002
Effective:
December 2001
Supersedes:
New
Air-Cooled Scroll Condensing Units
ACZ 010A – ACZ 039A
10 to 43 Tons, 35 to 150 kW
R-22, 60 Hertz

Table of Contents

Questions and Answers

  • T
    Tami ClarkAug 16, 2025
    What to do if the McQuay ACZ 028A Heat Pump compressor will not run?
    • B
      benjamin25Aug 16, 2025
      If the McQuay Heat Pump compressor will not run, first ensure the main switch is closed. Check for blown fuses or open breakers, inspecting electrical circuits and motor windings for shorts, overloads, and loose connections; replace the fuse or reset the breaker if necessary. Also, check if thermal overloads have tripped (they auto reset). Inspect the contactor or coil for defects and repair or replace if needed. Determine if a protection device has shut the system off and correct the cause. If no cooling is required, the compressor should start on a call for cooling. Check if the liquid line solenoid will not open and repair or replace the coil if needed. Inspect the motor for open or short circuits, or burnout. Finally, check all wire junctions and tighten all terminals.
  • A
    Ana ValdezAug 19, 2025
    What to do if my McQuay ACZ 028A Heat Pump has high discharge pressure?
    • M
      milleramyAug 19, 2025
      If your McQuay Heat Pump has high discharge pressure, it could be due to several reasons. First, there might be noncondensables in the system, which should be removed using authorized procedures. Another cause could be a refrigerant overcharge, so remove the excess. Check if the fan is running and inspect the electrical circuit. Dirty condenser coils can also cause this issue, so clean the coil. Lastly, the FanTrol might be out of adjustment, so adjust the FanTrol setting.
  • K
    Kathryn MartinAug 22, 2025
    Why is my McQuay Heat Pump compressor noisy or vibrating?
    • K
      Kyle Jackson DVMAug 22, 2025
      If your McQuay Heat Pump compressor is noisy or vibrating, it may be due to refrigerant flooding the compressor, so check the expansion valve setting. Another cause could be improper line support, in which case you should relocate or add supports. Finally, the compressor might be worn, requiring replacement.
  • Q
    qburkeAug 25, 2025
    What causes motor overload relays to open or blown fuses in McQuay Heat Pump?
    • A
      Amanda WadeAug 26, 2025
      Motor overload relays opening or blown fuses in your McQuay Heat Pump can be caused by several factors. These include: 1. Low voltage during high loads, in which case you should check the supply voltage. 2. Defective or grounded motor wiring, requiring you to replace the compressor. 3. Loose power wiring, so check all connections and tighten them. 4. High condensing temperature (see steps for high discharge pressure). 5. Unbalanced voltage, so check the voltage and contact the power company.
  • U
    udavisAug 28, 2025
    What to do if my McQuay ACZ 028A Heat Pump has low suction pressure?
    • M
      montoyahaileyAug 28, 2025
      If your McQuay Heat Pump has low suction pressure, it could be due to a lack of refrigerant, so check for leaks and repair and replace the refrigerant. Another cause could be a dirty evaporator, which needs to be cleaned chemically. A clogged filter-drier can also cause this, so replace it. Additionally, the expansion valve might be malfunctioning; check and adjust for proper superheat. Low condensing temperature can also be a factor; check discharge pressure control settings.
  • G
    Gary GarciaAug 30, 2025
    Why is my McQuay ACZ 028A's compressor losing oil?
    • A
      arobertsonAug 30, 2025
      If your McQuay Heat Pump's compressor is losing oil, it could be due to a lack of refrigerant, so check for leaks and repair them. Another cause could be suction superheat being too high, so adjust the superheat. Lastly, the crankcase heater might be burned out, requiring replacement.
  • J
    Jeremy GeorgeSep 2, 2025
    What causes low discharge pressure in a McQuay Heat Pump?
    • J
      James RichardsonSep 2, 2025
      Low discharge pressure in a McQuay Heat Pump can be caused by a faulty condenser control, so check the condenser control operation. It can also be caused by a low refrigerant charge, so check for leaks and add refrigerant. Another possible cause is low suction pressure; see the low suction pressure steps.
  • N
    nicole06Sep 5, 2025
    What causes high suction pressure in a McQuay ACZ 028A?
    • M
      Monica JacksonSep 5, 2025
      High suction pressure in a McQuay Heat Pump can be caused by an excessive load, so reduce the load or add capacity. It may also be caused by the expansion valve overfeeding, so check the remote bulb and regulate superheat.
  • P
    Paul PhillipsSep 7, 2025
    What causes a McQuay ACZ 028A Heat Pump unit to not load or unload?
    • J
      jfowlerSep 7, 2025
      If a McQuay Heat Pump unit will not load or unload, it could be due to a faulty controller sensor or a broken wire, requiring replacement. Another cause could be stages not set for the application, so adjust the thermostat setting.
  • C
    carrie99Sep 10, 2025
    Why does my McQuay ACZ 028A Heat Pump have a short load/unload interval?
    • D
      Donald ChapmanSep 10, 2025
      If your McQuay Heat Pump has a load/unload interval that is too short, it could be due to an erratic thermostat, in which case you should replace it. Another cause could be insufficient water flow, so adjust the flow.

Summary

Refrigerant Piping Guidelines

Suction Line Sizing and Routing

Guidelines for sizing and routing suction lines, including noise considerations.

Liquid Line Sizing and Operation

Liquid Line Requirements

Assuring proper liquid refrigerant flow to the expansion valve.

Control System Overview

Start-up and Shutdown Procedures

Step-by-step instructions for unit start-up and shutdown.

Unit Operation Details

Sequence of Operation

Describes the typical operational sequence of the unit.

Unit Protection and Alarms

Unit Shutdown Process

Details the sequence of events during a unit shutdown.

Electrical Data and Field Wiring

Field Wiring Requirements

Covers compliance with codes and wire requirements for field connections.

Table 5: Electrical Data (Single Point)

Details electrical data and wiring for single-point power connections.

Electrical Data: Amp Draw

Table 6: Compressor and Fan Motor Amp Draw

Lists rated and locked rotor amp draw for compressors and fans.

Electrical Data: Field Wiring

Table 7: Field Wiring Data (Single Point Power)

Provides field wiring data for single-point power connections.

Electrical Wiring Diagram

Typical Field Wiring Diagram

Illustrates the typical electrical connections for field wiring.

System Maintenance Procedures

Refrigerant Sightglass Observation

How to interpret the sightglass for refrigerant charge and moisture.

MicroTech II Controller Operation

Compressor Motor Protection

Details the solid-state motor protection for compressors.

FanTrol Head Pressure Control

Explains the fan control method for maintaining head pressure.

MicroTech II Controller Setpoints and Alarms

Table 10: Detailed Setpoints

Lists various configurable setpoints with default and range values.

Equipment Protection Alarms

Defines equipment protection alarms, conditions, and actions.

MicroTech II Controller Alarms and Unit Enable

Shutdown and Limit Alarms

Details shutdown and limit alarms, their causes, actions, and reset.

MicroTech II Controller Modes and Ambient Control

Low Ambient Start Sequence and Limits

Procedure for low ambient start sequence and automatic limit adjustments.

Using the MicroTech II Controller Interface

Menu Navigation Methods

Explains how to navigate through the controller's menu matrix.

MicroTech II Controller Menu Navigation

Changing Setpoint Values

Detailed steps for modifying setpoint values using the keypad.

MicroTech II Controller Menu Structure

Figure 12: Menu Matrix Overview

Visual representation of the controller's menu hierarchy.

MicroTech II Controller Alarm and Set Screen Definitions

Alarm Screen Definitions

Explains how active and logged alarms are displayed and cleared.

Set Screen Definitions

Guides on how to change setpoint values for various parameters.

MicroTech II Controller Setpoint Configuration (Part 2)

Compressor Anti-Recycle Timers

Configuring minimum run and stop times for compressors.

MicroTech II Controller Alarm Limits

Compressor Staging and Evaporator Pressure Alarms

Freeze Protection and Condenser Pressure Alarms

Service and Component Maintenance

Thermostatic Expansion Valve (TXV) Service

Filter-Drier Maintenance

Optional Controls and Hot Gas Bypass

SpeedTrol Head Pressure Control Function

Hot Gas Bypass System Operation

Hot Gas Bypass System Details

Hot Gas Bypass Piping Diagram

Hot Gas Bypass Adjustment Chart

Troubleshooting Guide

Troubleshooting Chart and Corrective Steps

A comprehensive chart listing common problems and their solutions.

McQuay ACZ 028A Specifications

General IconGeneral
BrandMcQuay
ModelACZ 028A
CategoryHeat Pump
LanguageEnglish

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