What causes a McQuay ACZ 010A compressor thermal switch to open?
A McQuay Heat Pump compressor thermal switch might open if it is operating beyond design conditions. To resolve this, add facilities so conditions are within allowable limits.
Overview of McQuay air-cooled condensing units, factory assembled, wired, and tested.
Procedure for checking units upon arrival for damage and verifying nameplate information.
Notes that installation must be performed by qualified personnel familiar with codes.
Guidelines for safely moving and lifting the unit to prevent damage.
Recommendations for mounting units on roofs or ground level on a solid, level foundation.
Requirements for accessibility to components for periodic maintenance and servicing.
Details minimum clearances required for air intake, discharge, and service access.
Methods to reduce sound transmission, including flexible connections and isolation techniques.
Recommends isolators for roof-mounted installations and lists part numbers and types.
Guidelines for installing water piping, including vibration eliminators and shutoff valves.
Further recommendations for water piping, including vents, drains, pressure indicators, and strainers.
Importance of adequate water volume for chiller stability and performance.
Instructions for mounting and connecting a water flow switch for unit shutdown.
Table detailing minimum and maximum flow rates for various pipe sizes.
Importance of proper refrigerant piping for system reliability and performance.
Guidelines for sizing and routing suction lines, including noise considerations.
Details on calculating suction line size and ensuring oil return.
Recommendation against underground suction lines and required precautions.
Recommendations for traps in long vertical refrigerant risers.
Guidelines for sizing liquid lines, ensuring liquid presence, and avoiding issues like migration.
Diagram showing the location of key components like control panel, compressors, and evaporator.
Description of the control center enclosure and its layout of components.
Checklist of pre-start-up procedures including system flushing, electrical checks, and oil levels.
Steps for starting the unit, checking oil, rotation, and superheat.
Typical operational sequence for ACZ units, including start-up, shutdown, and compressor staging.
Conditions that cause unit shutdown and activate alarms.
How unit operation is enabled and modes selected via keypad, input, or BAS.
How the controller manages condenser fan speed based on discharge pressure.
Process of unit shutdown, including compressor pump-down and crankcase heater activation.
Table detailing physical specs like dimensions, weight, and electrical data for specific models.
Table detailing physical specifications for larger ACZ models.
General requirements for field wiring, including codes, wire type, and disconnects.
Table showing power supply, wire size, and fuse/breaker recommendations.
Table detailing rated and locked rotor amps for compressors and fan motors.
Table specifying wiring details for standard power block and optional disconnect switch.
Explanations for electrical data tables, including fuse sizing, wire ampacity, and voltage limitations.
Clarification on RLA values for wiring sizing purposes.
Notes on single point power supply, disconnect requirements, and wire types.
Schematic showing the typical field wiring connections for the unit.
Dimensional drawings and connection sizes for smaller ACZ models.
Dimensional drawings and connection sizes for larger ACZ models.
Routine service checks, including electric leg readings available on the MicroTech II display.
States no routine lubrication is required as fan motor bearings are permanently lubricated.
Warning about electric shock hazard and requirement to retighten terminals every six months.
Information on condenser construction and cleaning procedures, including warnings about chemicals.
Monthly observation of the sightglass to check refrigerant charge and moisture conditions.
Introduction to the MicroTech II controller's features for efficiency and troubleshooting.
Description of the controller's menu structure, security, and diagnostic capabilities.
How compressors are staged on/off via thermostat and lead/lag logic.
Details on solid-state motor protection and internal line breakage for compressors.
Explanation of FanTrol's automatic head pressure control using condenser fan staging.
Tables detailing analog and digital inputs and outputs for the controller.
Explanation of setpoints stored in memory and password levels for access.
Table listing default and range values for various unit setpoints.
Description of alarms that cause rapid compressor shutdown.
Table detailing conditions, actions, and reset methods for shutdown alarms.
Table detailing conditions, actions, and reset methods for limit alarms.
How unit enable is controlled via setpoints and input sources.
Table showing how unit enable is set based on control source.
Options for selecting COOL or TEST operating modes.
How the unit starts under low ambient conditions, bypassing pressure alarms.
Procedure for restarting the unit after low ambient conditions cause a shutdown.
Setpoint ranges that adjust automatically based on options or mode.
Range for low ambient lockout temperature based on SpeedTrol setting.
Logic for designating lead/lag compressors based on start count.
Conditions that override capacity control, like low evaporator or high discharge pressure.
How digital outputs like alarms, solenoids, and fans are controlled.
Description of the MicroTech II controller's display and keypad layout.
Basic procedures for using the controller, including navigation and reading information.
Methods for navigating the controller's menu matrix using ARROW and MENU keys.
Function of the MENU key for switching between shortcut and scrolling modes.
Overview of different menu screens for viewing status, alarms, and setpoints.
Procedure for changing setpoint values using the ENTER and ARROW keys.
Detailed steps for changing setpoints, including using ENTER and ARROW keys.
Hierarchical diagram showing the controller's menu structure and navigation paths.
Explanation of the menu structure and how to access different screens.
Detailed explanation of various VIEW screens and their content.
Description of the VIEW UNIT STATUS screen and unit state indicators.
Display of outside ambient temperature.
Screens showing compressor state, hours, and start counts.
Displays for evaporator and condenser pressures and temperatures.
Display showing active fan stages.
Explanation of active alarm screens, clearing alarms, and alarm log.
General procedures for changing setpoints using the SET menus.
Settings for Unit Enable and Control Source.
Settings for Available Modes and reminder for ON/OFF switch.
Settings for CLOCK (date and time).
Settings for Units (°F/psi) and Language (ENGLISH).
Settings for Protocol, Ident Number, and Baud Rate for BAS.
Settings for Evaporator Refrigerant pressure sensor offset.
Settings for Condenser Refrigerant pressure sensor offset.
Settings for Outside Ambient Temperature Sensor offset.
Settings for entering passwords to access protected parameters.
Settings for anti-recycle timers (Stop-Start, Start-Start).
Settings for inter-stage time delays for compressor staging.
Settings for low evaporator pressure hold, unload, and stop limits.
Settings for Evap Freeze, Low Evap Pressure Delay, and Evap Flow Proof.
Settings for high condenser pressure shutdown and stage down limits.
Settings for Phase/Voltage protection and Low Ambient Lockout.
Settings for the number of fans and SpeedTrol option.
Settings for fan stage ON pressures.
Settings for fan stage OFF pressures.
Function of the TXV in maintaining superheat for compressor life.
Guidelines for monitoring and replacing filter-driers based on pressure drop.
Notes on the liquid line solenoid valve and its role in pump-down.
How SpeedTrol modulates fan speed for low ambient operation and head pressure control.
Purpose and function of the hot gas bypass system for maintaining evaporator pressure.
Piping and adjustment details for the hot gas bypass system.
Diagram illustrating the piping for the hot gas bypass system.
Chart showing adjustment ranges for the hot gas bypass valve.
Table listing problems, possible causes, and corrective steps for unit issues.
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General