York YMC2 A - User Manual

Questions and Answers

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Richard RosarioAug 3, 2025
What to do if my York Chiller has abnormally low suction pressure?
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  Scott GrossAug 3, 2025
  If your York Chiller is experiencing abnormally low suction pressure, it could be due to: * Insufficient refrigerant. Check for leaks and add refrigerant to the system. * A variable orifice problem. Remove any obstruction. * Dirty or restricted evaporator tubes. Clean the evaporator tubes. * Insufficient load for the system capacity. Check the capacity control operation and the setting of the low water temperature shutdown setpoint.
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Stephanie BrownAug 8, 2025
What to do if the suction pressure is abnormally low in my York Chiller?
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  Kelli RodriguezAug 8, 2025
  If you notice an abnormally low suction pressure in your York Chiller, it could be due to several reasons. First, there might be an insufficient charge of refrigerant, so check for leaks and add refrigerant to the system. Another possible cause is a variable orifice problem, which would require removing any obstruction. Also, check if the evaporator tubes are dirty or restricted and clean them if necessary. Lastly, the system might have insufficient load for its capacity; in this case, check the capacity control operation and the setting of the low water temperature shutdown setpoint.
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John RichardsonAug 14, 2025
Why does my York Chiller have abnormally high discharge pressure?
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  Brandon HoltAug 14, 2025
  Abnormally high discharge pressure in your York Chiller can be due to several reasons: * Dirty or scaled condenser tubes. If this is the case, clean the condenser tubes and check the water conditioning. * High condenser water temperature. To resolve this, reduce the condenser water inlet temperature and check the cooling tower and water circulation. * Insufficient condensing water flow. Increase the quantity of water through the condenser to the correct value.
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Erika HerreraAug 19, 2025
Why is the discharge pressure abnormally high in my York YMC2 A Chiller?
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  Roy StokesAug 19, 2025
  Abnormally high discharge pressure in your York Chiller can be caused by several factors. The condenser tubes might be dirty or scaled, requiring cleaning and a check of the water conditioning. The condenser water temperature could be too high; in this case, you should reduce the condenser water inlet temperature, checking the cooling tower and water circulation. Finally, there might be insufficient condensing water flow, so increase the quantity of water through the condenser to the proper value.
B
Brent GarciaAug 25, 2025
How to fix high evaporator pressure in a York Chiller?
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  Michael SuarezAug 25, 2025
  High evaporator pressure in your York Chiller may be caused by: * Capacity control failing to load. Inspect the PRV (if applicable), VGD, and hot gas bypass (if applicable) positioning circuits. * System overload. Ensure that the capacity control devices and speed increased (without overloading the motor) until the load decreases.
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Alison BensonAug 28, 2025
How to fix high evaporator pressure in York Chiller?
- A
  Alexis GibbsAug 29, 2025
  High evaporator pressure in a York Chiller can occur if the capacity control fails to load. In this case, you should check the PRV (if applicable), VGD, and Hot Gas Bypass (if applicable) positioning circuits. Another reason could be system overload. Ensure that the capacity control devices and speed are increased (without overloading the motor) until the load decreases.

Summary

Important Safety and Document Information

General Safety Guidelines

Discusses inherent hazards and personnel responsibilities for safe operation and maintenance.

Safety Symbols Explained

Explains the meaning of warning symbols used throughout the document for hazard identification.

Document Overview and Maintenance Programs

Document Changeability and Revisions

Policy on document updates and user responsibility to verify applicability of information.

Associated Literature

Lists related manuals and their form numbers for further reference.

Conditioned Based Maintenance (CBM)

Introduces the YORK Conditioned Based Maintenance (CBM) program as an alternative to traditional maintenance.

Chiller Nomenclature and Specifications

System Nomenclature

Explains the coding system for identifying chiller models and their configurations.

Compressor Nomenclature

Details the nomenclature used for compressor specifications and design levels.

Vessel Nomenclature

Defines the naming conventions for vessel components and their characteristics.

Variable Speed Drive (VSD) Nomenclature

Explains the coding system for variable speed drive (VSD) models and their specifications.

Section 1: System Fundamentals

System Components Overview

Overview of the YMC2 chiller as a factory-packaged unit with key components.

Compressor Details

Details the single-stage centrifugal compressor, its motor, and impeller design.

Motor Description

Describes the hermetic permanent magnet high-speed motor with magnetic bearings.

Heat Exchangers

Details the construction and features of the evaporator and condenser heat exchangers.

Evaporator Function

Describes the evaporator as a shell and tube, hybrid falling film, and flooded type heat exchanger.

Condenser Function

Explains the condenser as a shell and tube type with a discharge gas baffle and subcooler.

Waterboxes

Details the construction, pressure ratings, and connections of the compact waterboxes.

Refrigerant Flow Control

Explains how the variable orifice controls refrigerant flow based on level sensor input.

Optional Service Isolation Valves

Information on the use and requirement of isolation valves for refrigerant service.

Optional Hot Gas Bypass

Describes the function of hot gas bypass for turndown and capacity modulation.

OptiView Control Center

Overview of the OptiView Control Center's function in unit operation and energy management.

Variable Speed Drive (VSD)

Explains the VSD's role in varying compressor speed for efficiency and control.

System Operation Description

Describes how the chiller operates, its components, and control logic.

Capacity Control Methods

Details methods used to modulate chiller capacity, including speed and prerotation vanes.

Variable Geometry Diffuser (VGD)

Explains VGD's function in mitigating stall and controlling capacity.

Hot Gas Bypass (HGBP)

Describes HGBP as an optional means for maximum turndown and capacity reduction.

Section 2: System Operating Procedures

Pre-Starting Procedures

Steps to take before starting the chiller, including checking the control center display.

Chiller Start-Up

Procedure for starting the chiller, including pump operation and RUN key sequence.

Chiller Operation

How the chiller varies capacity to maintain setpoint using various control methods.

Condenser Water Temperature Control

Guidelines for managing condenser water temperature for optimal chiller performance.

Operating Logs

Importance of maintaining a daily record of system operating conditions.

Need for Maintenance or Service

Guidance on troubleshooting and contacting Johnson Controls for issues.

Stopping the System

Procedure for safely stopping the chiller using the control panel or safety stop switch.

Prolonged Shutdown

Steps for shutting down the chiller for extended periods, including draining and leak testing.

Section 3: Maintenance

Renewal Parts

Information on obtaining YMC2 Unit Renewal Parts using the specified manual.

Leak Testing Procedures

Procedure for leak testing the refrigerant side of the system using R-134a compatible detector.

Conducting R-22 Pressure Test

Steps to test for leaks using R-22 and dry nitrogen after refrigerant removal.

Vacuum Testing

Procedure for vacuum testing the system after pressure testing, ensuring dryness.

Vacuum Dehydration

Detailed procedure for dehydrating the system using a vacuum pump and wet bulb indicator.

Refrigerant Charging

Procedure for charging refrigerant to avoid freezing and minimize moisture entry.

Checking Refrigerant Charge

Method to check and trim the refrigerant charge when the system is shut down.

Handling Refrigerant for Repairs

Steps for handling refrigerant when opening the system for repairs, including isolation.

Megging the Motor

Procedure for testing motor winding resistance by a qualified technician.

Condenser and Evaporator Maintenance

Importance of keeping condenser and evaporator water sides clean and free from scale.

Chemical Water Treatment

Importance of water analysis and treatment to prevent corrosion and scale.

Cleaning Evaporator and Condenser Tubes

Identifying potential evaporator performance issues related to fouled tubes.

Tube Fouling Causes

Discusses types of tube deposits (rust, sludge, scale) and their impact on heat transfer.

Tube Cleaning Procedures

Procedure for cleaning tubes using a soft bristle brush to remove dirt and sludge.

Acid Cleaning of Tubes

Procedure for cleaning tubes with hard scale deposits using acid solutions.

Commercial Acid Cleaning Services

Recommends using specialized commercial services for acid cleaning.

Testing for Tube Leaks

Procedure for detecting and locating tube leaks in evaporator and condenser systems.

Compressor Maintenance

Maintenance for the compressor assembly, focusing on magnetic bearing observation.

Electrical Controls Information

References the manual for OptiView Control Center operations.

Maintenance Inspections for YORK YMC² Chillers

Daily Inspections

Daily checks of OptiView display, water parameters, and compressor status.

Weekly Inspections

Weekly checks include refrigerant charge and condenser tube condition assessment.

Monthly Inspections

Monthly checks cover VSD values, setpoints, water flows, and motor starter operation.

Annual Inspections

Annual checks include heat exchangers, motor winding resistance, electrical components, and VSD.

SI Metric Conversion

Temperature Conversion

Provides formulas and examples for converting Fahrenheit to Celsius for temperature and range.

York YMC2 A Specifications

General

Refrigerant	R-134a
Capacity	Variable
Compressor Type	Magnetic Bearing Centrifugal
Operating Temperature Range	40°F to 95°F
Flow Rate	Variable
Power Supply	380-480V/3Ph/60Hz
Weight	Varies by model