Dunham-Bush ACXi 165-5SP-LN

Questions and Answers

D
David WhiteAug 5, 2025
How to troubleshoot a Dunham-Bush Chiller that will not start?
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  Paul WellsAug 5, 2025
  If your Dunham-Bush Chiller unit isn't starting, several factors could be at play. Here's what to check: * **Power Supply:** Begin by verifying the main disconnect switch and fuses. * **Control Power:** Inspect the control transformer fusing. * **Circuit Breakers:** Ensure the compressor circuit breakers are closed. If they trip, examine the compressor itself. * **Undervoltage Relay:** Look for power supply issues like low voltage or phase imbalance. Correct any problems and then press the reset button. * **Flow Switch:** Start the pumps and check the flow switch. * **Compressor Switch:** Turn the compressor switch on and check the alarm status, addressing any issues. * **Microcomputer Shutdown:** Press the reset button to clear any microcomputer shutdowns.
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Brett FrenchAug 10, 2025
What to do if Dunham-Bush ACXi 165-5SP-LN Chiller compressor hums but does not start?
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  Jordan FrancisAug 10, 2025
  If your Dunham-Bush Chiller's compressor hums but doesn't start, it could be due to: * **Low Voltage:** Check the voltage at the main entrance and at the unit itself. If the voltage is low at the main entrance, consult your power company. If it's normal at the main entrance but low at the unit, increase the wire size to the unit. The voltage must be within 10% of the motor's nameplate rating. * **Missing Phase:** For a 3-phase unit, check the fuses and wiring to ensure all three phases have power. * **Starter/Contactor Issues:** Inspect the contacts and time delay on part-wind start components.
B
Brian MaddenAug 17, 2025
What to do if Dunham-Bush ACXi 165-5SP-LN Chiller compressor won't start after pushing reset button?
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  Patricia PowellAug 17, 2025
  If your Dunham-Bush Chiller's compressor won't start when the reset button is pushed, and the check light is off, consider these possibilities: * **Cooling Not Required:** The simplest reason might be that the system doesn't need to cool; try applying a load. * **Time Delay:** The computer's time delay might be active; wait up to 15 minutes. * **Undervoltage Relay:** Refer to section 1.(d.) for troubleshooting undervoltage relay issues. * **Flow Switch:** Refer to section 1.(e.) for troubleshooting flow switch issues. * **Compressor Switch:** Refer to section 1.(f.) for troubleshooting compressor switch issues. * **Signal Light:** The signal light might be burned out; check the bulbs. * **Wiring:** There may be a wiring problem. Check the wiring against the provided drawing.
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georgelisaAug 29, 2025
What causes a freeze warning on a Dunham-Bush ACXi 165-5SP-LN Chiller?
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  Michael FlemingAug 29, 2025
  If your Dunham-Bush Chiller displays a freeze warning, it could be due to: * **Setpoint Too Low:** Check the leaving water setpoint on the microcomputer. * **Rapid Load Changes:** The load on the package must decrease at a reasonable rate for automatic control to function correctly.
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Anna MoyerNov 21, 2025
Why is there low suction in my Dunham-Bush ACXi 165-5SP-LN?
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  Kimberly PageNov 21, 2025
  If the suction is low in your Dunham-Bush Chiller, it could be caused by several factors: * **Inadequate Feed to Evaporator:** Check the main expansion valve superheat. * **Inadequate Refrigerant Charge:** See information on charging in Section 5.7. * **Fouling of Water Side of Evaporator:** At high load, check the Evaporator approach (See Section 5.4). If the approach is more than 2°F above the clean valve value, fouling is probably the cause. Clean the tube. * **Inadequate Chilled Water Flow:** Measure the pressure drop across the vessel and determine gpm from Figure 3.3. If gpm is low, check the chilled water pump, valves, and strainers. * **Too Much Oil in System:** If all oil level sight glasses are full at all times, remove oil until the oil level shows at the top of the g...

Summary

1.0 INTRODUCTION

1.1 PRODUCT IDENTIFICATION

Explains the product model nomenclature.

2.0 INSTALLATION

2.1 GENERAL

General information about packaged chillers.

2.1.1 APPLICATION PRECAUTIONS

Instructions for proper application of the chilling machine.

2.1.2 CHILLED WATER FLOW

Details on maintaining steady flow for stable operation.

2.2 INSPECTION

Steps for inspecting the unit upon delivery.

2.3 RIGGING

General guidelines for rigging and moving the unit.

2.4 SPACE REQUIREMENTS AND CLEARANCE

Guidelines for unit placement and necessary clearances for operation and servicing.

2.5 FOUNDATION

Requirements for unit foundations and support structures.

2.6 VIBRATION ISOLATION

Information on installing vibration isolators.

2.7 PIPING CONNECTIONS

Guidance on connecting evaporator water piping and system preparation.

2.8 ELECTRICAL WIRING

Precautions for connecting power wiring to the unit.

2.9.1 CONNECTIONS

How to connect field-installed controls.

2.9.2 SETTINGS

Factory settings and control adjustments.

2.10 REQUEST FOR START-UP REPRESENTATIVE

Procedure for requesting a start-up representative.

3.0 OPERATION

3.1 GENERAL

Guidelines for starting up the unit by a technician.

3.2 UNIT PIPING

Information on refrigerant circuits and piping schematics.

3.3 SYSTEM WATER FLOW RATE

How to measure and determine chilled water flow rate.

3.4 STANDARD AMBIENT UNIT OPERATION (65°F MINIMUM AMBIENT) INCLUDING OVERNIGHT SHUT-DOWN AND MORNING RESTART

Operational procedures for standard ambient conditions.

3.4.1 AIR COOLED CHILLER START-UP PACKAGE

Procedures before unit startup.

3.5 SYSTEM START UP

Steps for system startup, checking voltage and rotation.

3.6 SHUT-DOWN (OVERNIGHT OR WEEKEND)

Procedure for shutting down the unit for short periods.

3.7 SEASONAL SHUT-DOWN PROCEDURE

Steps for shutting down the unit for the season.

3.8 SEASONAL START-UP PROCEDURE

Steps for starting up the unit after seasonal shutdown.

3.9 SAFETY RELIEF VALVES

Information on safety relief valve requirements.

3.10 REFRIGERATION CYCLE -MULTIPLE COMPRESSOR ACXI

Description of the refrigeration cycle for ACXI units.

3.11 FAN CYCLING

How fan stages operate based on head pressure.

3.12 LIQUID INJECTION

Function of the liquid injection system for motor cooling.

3.13 HYDRAULIC CAPACITY CONTROL SYSTEM

Explanation of the capacity control system.

4.0 ELECTRICAL

4.1 ELECTRICAL DATA

Technical specifications for electrical data.

4.2 WIRING DIAGRAM

Reference to typical wiring diagrams.

4.3 TYPICAL OPERATION

Conditions required for compressor startup and operation logic.

4.4 MICROCOMPUTER CONTROLLER

Overview of the microcomputer control system.

4.4.1 TO DISPLAY DATA FROM THE MENU

Steps to display various types of data from the menu.

4.4.2 TO RESET ALL CONTROL POINTS TO COMPUTER CONTROL

Procedure to reset control points to computer control.

4.4.3 TO DISPLAY ALARMS

How to view active alarms and their codes.

4.4.4 TO BECOME AUTHORIZED

Steps to gain authorization for programming mode.

4.4.5 TO ALTER SETPOINT DATA

How to change setpoint values.

4.4.6 TO CALIBRATE TEMPERATURE AND PRESSURE SENSORS

Procedure to calibrate temperature and pressure sensors.

4.4.7 TO SET DATE AND TIME

Steps to set the unit's date and time.

4.4.8 TO DISPLAY DATA WITHOUT ACCESSING MENU

Method to display data using function keys.

4.4.9 UNIT SCHEDULE OF OPERATION

How to set up a seven-day operating schedule.

4.5 CONTROL FUNCTIONS

Overview of various control functions.

4.5.1 Chilled Water Pump Interlock And Flow Switch (CWP And CWFS)

Role of pump interlock and flow switch.

4.5.2 Customer Control Interlock

Enabling/disabling unit operation via external controller.

4.5.3 Anti-Recycle Timer (Microcomputer)

Prevents rapid compressor restarts after shutdown.

4.5.4 Load Control (Microcomputer)

How the microcomputer controls compressor loading.

4.5.5 Ramp Control (Microcomputer)

Ability to vary load time from start.

4.5.6 Current Limiting (Microcomputer)

Limits compressor current draw via setpoints.

4.5.7 Staging Control (Microcomputer)

Logic for adding/removing compressors based on load.

4.5.8 Manual Lead-Lag Control (Microcomputer)

Selecting lead/lag compressor for multi-compressor units.

4.5.9 Manual Load-Unload Control (Microcomputer)

Placing a compressor into manual control mode.

4.5.10 Chilled Water Reset and Customer Control Interlock (Optional)

Adjusting setpoint with external signal and control interlock.

4.5.11 Variable Fan Speed Control (Optional)

Using VFD to control fan speed based on discharge pressure.

4.5.12 Sump Heater Control

Function of oil sump heaters and pre-start requirements.

4.6 SAFETY FUNCTIONS

Overview of safety functions protecting the unit.

4.6.1 Control Power Loss (Microcomputer)

Handling of power loss and automatic/manual restart.

4.6.2 Low Pressure Cut-off (Microcomputer)

Shuts down compressor on low evaporator pressure.

4.6.3 Evaporator Freeze Shutoff (Microcomputer)

Shuts down unit if leaving water temp drops too low.

4.6.4 High Pressure Cut-off (Microcomputer)

Shuts down compressor on high discharge pressure.

4.6.5 Oil Level Switch (LS)

Shuts down compressor on low oil level.

4.6.6 Overload Protector (OL)

Protects compressor from overcurrent and overheating.

4.6.7 Phase Control Relay (PCR)

Protects against electrical supply malfunctions.

4.6.8 Sensor Alarm (Microcomputer)

Detects abnormal analog sensor values.

4.6.9 No-Stop Alarm (Microcomputer)

Alarm for compressor failure to stop.

4.6.10 Low Differential Pressure Alarm (Microcomputer)

Shuts down unit for low lubrication pressure.

5.0 MAINTENANCE

5.1 GENERAL

Importance of regular inspection and maintenance.

5.2 PERIODIC INSPECTION

Recommendations for periodic inspection and recording.

5.3 MONTHLY INSPECTION

Tasks for monthly inspection of components.

5.4 VESSEL MAINTENANCE

Maintenance of evaporator and condenser surfaces.

5.4.1 GENERAL

Importance of clean heat transfer surfaces.

5.4.2 WATER SIDE CLEANING OF EVAPORATOR

Procedure for cleaning evaporator water side.

5.5 AIR COOLED CONDENSER CLEANING

How to clean condenser coils.

5.6 ELECTRICAL MALFUNCTION

Protecting compressor motors from electrical issues.

5.7 REFRIGERANT CHARGE

Procedures for checking and adding refrigerant.

5.7.1 GENERAL

Factory charge and checking procedure.

5.7.2 AIR COOLED PACKAGES

Determining subcooling for charge verification.

5.8 OIL CHARGE

Proper oil charge and type, avoiding damage.

5.9 TROUBLESHOOTING

Common symptoms, causes, and remedies for unit issues.

5.10 SAMPLE LOG SHEET

Recommended log sheet for recording operating data.