Daikin AGZ 125D User Manual

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Operating & Maintenance Manual

OMM 1166-1

Group: Chiller

Part No. OMM1166-1

Effective: March 2014

Air-Cooled Scroll Compressor Chiller

AGZ025D – AGZ190D (Rev 0A) 25 to 190 Tons

50 - 60-Hertz, R-410A

Software Version 251699201

© 2014 Daikin Applied

Table of Contents

Table of Contents2
- Introduction3
  - Glycol Solutions5
  - Operating/Standby Limits9
- Pressure Drop Curves9
  - Minimum Allowable Flow Rates9
  - Pressure Drop Curves10
Microtech III Controller13

Questions and Answers:

T
Terry FosterAug 20, 2025
Why is the discharge pressure high on my Daikin AGZ 125D?
- E
  Elizabeth PayneAug 20, 2025
  High discharge pressure in your Daikin Chiller can stem from several issues. Noncondensables might be present in the system, requiring extraction using approved procedures. The system could be overcharged with refrigerant, necessitating removal of the excess and a check of liquid subcooling. Ensure the optional discharge shutoff valve is fully open. Verify that the FanTrol wiring is correct and that the fan is running by checking its electrical circuit and motor. A dirty condenser coil can also cause this issue, so clean it thoroughly. Finally, correct any air recirculation problems.
A
Angel WalkerAug 23, 2025
Why is my Daikin AGZ 125D Chiller compressor noisy or vibrating?
- P
  Patrick BishopAug 23, 2025
  If your Daikin Chiller compressor is making excessive noise or vibrating, start by checking the refrigerant charge, as low or no refrigerant can cause this. Ensure the compressor is running in the correct direction by verifying the unit and compressor phasing. Inspect the piping support on both the suction and discharge lines, relocating, adding, or removing hangers as needed. Finally, examine the compressor isolator bushings for wear and replace if necessary, and consider whether the compressor itself is worn, potentially requiring replacement.
C
Carlos HansenAug 28, 2025
What causes high suction pressure in Daikin Chiller?
- M
  Maria HowellAug 28, 2025
  High suction pressure in a Daikin Chiller may result from several causes. Check the control settings to ensure the water temperature isn't excessively high. An excessive load on the system can also lead to this issue; reduce the load or add additional equipment. If the expansion valve is overfeeding, inspect the remote bulb and regulate the superheat. Lastly, verify that the compressors are running in the correct direction by checking for proper phasing.
B
briankeyAug 30, 2025
What to do if Daikin AGZ 125D Chiller compressor oil level is too high or too low?
- P
  Paul PhillipsAug 31, 2025
  If the oil level in your Daikin Chiller compressor is too high or too low, consider these potential causes. Oil may be hanging up in the piping, so review the refrigerant piping and correct as necessary. If the oil level is genuinely low, check for leaks and add oil. Inspect the oil line fittings for looseness and tighten them. If the level is too high, adjust the thermal expansion valve. Insufficient water flow can also cause a high oil level, so adjust the flow. Excessive liquid in the crankcase can also elevate the oil level; check the crankcase heater, reset the expansion valve for higher superheat, and verify the liquid line solenoid valve operation. Short cycling can also affect oil levels; stabilize the load or increase the staging interval.
M
Melissa HinesSep 2, 2025
What to do if the Daikin AGZ 125D discharge pressure is low?
- J
  James MorrisSep 2, 2025
  Low discharge pressure in a Daikin Chiller can be caused by several factors. Refrigerant flood back is one possibility, requiring correction. If wind is blowing directly into the coil at low ambient temperatures, shield the coil or install wind guards. A faulty condenser temperature regulation system should be checked for proper operation. Insufficient refrigerant in the system can also cause this; check for leaks, repair them, and add charge. Additionally, low suction pressure and only one compressor operating can contribute to low discharge pressure.
J
Jennifer GonzalezSep 4, 2025
Why is my Daikin Chiller compressor losing oil?
- W
  William BrownSep 5, 2025
  If your Daikin Chiller compressor is losing oil, start by checking for refrigerant leaks and repairing them, then add refrigerant as needed. Also, check if the suction superheat is too high and adjust it accordingly. Finally, inspect the crankcase heater for burnout and replace it if necessary.
J
jkruegerSep 7, 2025
What to do if Daikin AGZ 125D Chiller compressor will not stage up?
- J
  Jessica SmithSep 7, 2025
  If your Daikin Chiller compressor isn't staging up, the issue might stem from a defective capacity control, which would need replacement. Alternatively, there could be a faulty thermostat stage or a broken wire, also requiring replacement. Finally, ensure that the stages are correctly set for the specific application by resetting the thermostat settings.
B
Billy CampbellSep 9, 2025
Why are the motor overload relays or circuit breakers open on my Daikin AGZ 125D Chiller?
- D
  Dale HuynhSep 10, 2025
  If the motor overload relays or circuit breakers in your Daikin Chiller are opening, it could be due to low voltage during high load conditions; check the supply voltage for excessive line drop. Defective or grounded wiring in the motor can also cause this, necessitating replacement of the compressor motor. Inspect for loose power wiring or burnt contactors, tightening all connections. Also, high condenser temperature and a power line fault causing unbalanced voltage can trigger this issue.
S
Shannon LopezSep 12, 2025
What causes the compressor thermal protection switch to open on a Daikin AGZ 125D Chiller?
- M
  martinezandreaSep 12, 2025
  If the compressor thermal protection switch on your Daikin Chiller is open, it could be due to operating beyond design conditions, requiring additional facilities to bring conditions within allowable limits. A partially shut discharge valve can also cause this, so ensure it's fully open. Additionally, a blown compressor internal gasket, voltage range issues or imbalance, high superheat, or compressor bearing failure can trigger this switch.

Daikin AGZ 125D Specifications

General

Brand	Daikin
Model	AGZ 125D
Category	Chiller
Language	English

Summary

Introduction

General Description

Overview of the air-cooled scroll compressor chiller's design and components.

Nomenclature

Explanation of the model designation system for AGZ chillers.

Hazard Identification Information

Details on DANGER, WARNING, and CAUTION safety messages.

Ambient Air Temperature Limitations

Specifies maximum and minimum operating ambient temperatures for the unit.

Water Flow Limitations

Discusses evaporator flow rate and pressure drop considerations for proper control.

Glycol Solutions

Altitude Correction Factors

Adjustments for unit performance based on altitude.

Evaporator Temperature Drop Factors

Factors for adjusting performance with different evaporator temperature drops.

Operating/Standby Limits

Minimum Allowable Flow Rates

Defines minimum flow rates for stable operation in different system types.

Pressure Drop Curves

Constant-Chilled Water Flow Systems

Minimum flow rates for constant flow chilled water systems.

Variable-Chilled Water Flow Systems

Minimum flow rates for variable flow chilled water systems.

MicroTech® III Controller

Overview

Introduction to the controller's features and benefits for efficient operation and troubleshooting.

Controller Inputs and Outputs

Lists analog and digital inputs and outputs for the main controller.

Setpoints

Details on unit-level and circuit-level setpoints, including default and range values.

Security

Information on password protection for accessing and changing setpoints.

Unit Functions

Definitions and explanations of unit-level functions like LWT Slope and Pulldown Rate.

Circuit Functions

Definitions, control logic, and states for refrigerant circuits.

Alarms

Classification and description of unit fault, warning, and problem alarms.

Events

Logging and handling of unit and circuit events that are not severe enough for alarms.

Using the Controller

Guidance on navigating the controller interface, menus, and modes.

Optional Low Ambient Fan VFD

VFD Interface (HMI)

Description of the Human Machine Interface (HMI) for VFD control.

LCD Display

Explanation of the data displayed on the VFD's LCD screen.

Recommended Periodic Inspection

Optional BAS Interface

Information on integrating the chiller with a Building Automation System.

Startup

Pre Start-up

Checks and preparations required before starting the chiller.

Start-Up

Step-by-step procedure for initiating chiller operation.

Shutdown

Procedures for temporary and extended chiller shutdowns.

Operation

Hot Gas Bypass (Optional)

Explanation of the hot gas bypass system for low load operation.

VFD Low Ambient Control (Optional)

How VFD controls fan speed for low ambient operation.

Compressor Communications

Details on the compressor communication module, its features, and alerts.

System Adjustment

Procedures for adjusting system superheat and liquid subcooling for peak performance.

Refrigerant Charging

Steps for proper refrigerant charging and checking subcooling/superheat.

Unit Maintenance

General

Routine service checks and recommended maintenance schedule.

Compressor Maintenance

Maintenance requirements for scroll compressors, including oil type.

Condensers

Maintenance procedures for air-cooled condensers, including cleaning.

Planned Maintenance Schedule

A detailed schedule of weekly, monthly, and annual maintenance tasks.

Service

R-410A

Terminology, safety, and handling precautions for R-410A refrigerant.

POE Lubricants

Information on the use and handling of POE lubricants with compressors.

Filter-Driers

Guidelines for replacing filter-driers based on pressure drop and moisture indication.

Evaporator

Description of evaporator types and their protection features.

AGZ-D Troubleshooting Chart

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