Daikin AGZ 025D User Manual

Daikin AGZ 025D

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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:

M
Mr. Caleb Brown MDAug 20, 2025
Why is the discharge pressure high on my Daikin AGZ 025D Chiller?
- J
  joshuahigginsAug 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.
R
Russell LopezAug 22, 2025
Why is my Daikin Chiller compressor noisy or vibrating?
- N
  Nichole JacksonAug 22, 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.
V
Veronica ArnoldAug 27, 2025
What causes high suction pressure in Daikin AGZ 025D?
- T
  Tammy BryanAug 27, 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.
T
Timothy GonzalezAug 30, 2025
What to do if Daikin Chiller compressor oil level is too high or too low?
- A
  Amanda PaulAug 30, 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.
R
rodriguezpaulaSep 1, 2025
What to do if the Daikin AGZ 025D discharge pressure is low?
- J
  jonathan31Sep 1, 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.
R
Rebecca MooreSep 4, 2025
Why is my Daikin AGZ 025D compressor losing oil?
- R
  ramirezjohnSep 4, 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.
K
keithmartinSep 6, 2025
What to do if Daikin AGZ 025D Chiller compressor will not stage up?
- W
  William BlankenshipSep 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.
W
William WilliamsonSep 9, 2025
Why are the motor overload relays or circuit breakers open on my Daikin AGZ 025D?
- T
  tannerjodySep 9, 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
Samantha WiseSep 12, 2025
What causes the compressor thermal protection switch to open on a Daikin Chiller?
- L
  lisa66Sep 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 025D Specifications

General

Brand	Daikin
Model	AGZ 025D
Category	Chiller
Language	English

Summary

MicroTech® III Controller

Controller I/O & Modules

Setpoints & Configuration

Storing, viewing, and adjusting unit and circuit setpoints.

Controller Menu Navigation & Screens

Security

Password Access & Editing

Procedures for entering and editing passwords.

Unit Enable & Mode Selection

Enabling & Mode Settings

Evaporator Pump Control

Pump Operation & Selection

LWT Target & Reset

LWT Target Setting & Reset

How the LWT target is set and adjusted.

Compressor Staging & Overrides

Staging Logic & Capacity Limits

Circuit Functions & Control

Circuit Definitions & Logic

Circuit States & Compressor Control

Condenser Fan & EXV Control

Condenser Fan Staging & VFD

EXV Control Logic

Alarms & Events

Unit Alarms

Unit fault, problem, and warning alarms with triggers and actions.

Circuit Alarms & Events

Troubleshooting Chart

Compressor Issues

Troubleshooting for compressor starting, noise, oil, and staging problems.

Pressure Issues

Troubleshooting for high/low discharge and suction pressures.

Other Troubleshooting

Troubleshooting for oil levels, motor overloads, and thermal protection.

Startup & Maintenance

Start-Up Procedures

Steps for inspecting and starting the chiller.

Unit Maintenance Schedule

Routine service checks and maintenance schedule.

Service & Refrigerant Handling

R-410A Safety & POE Lubricants

Safety precautions for R-410A and POE oil handling.

Refrigerant Charging & Filter-Driers

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