Johnson Controls York YK Installation guide

035-27332-100
Form Number: 160.76-O1 (421)
Supersedes: 160.76-O1 (321)
Operations and Maintenance
Issue Date: 2021-04-25
Model YK (Style H), R-134a and R-513A
With OptiView Control Center for Electromechanical
Starter, Solid-State Starter, and Variable Speed Drive

2 Model YK (Style H), R-134a and R-513A

Contents
ContentsGeneral safety guidelines.............................................................................................................................. 5
Safety symbols..................................................................................................................................... 5
Changeability of this document......................................................................................................... 6
Revision notes...................................................................................................................................... 6
Associated literature........................................................................................................................... 6
Conditioned based maintenance...................................................................................................... 7
Nomenclature...................................................................................................................................... 8
Description of system and fundamentals of operation............................................................................ 9
System operation description............................................................................................................ 9
Capacity control................................................................................................................................. 10
System operating procedures.................................................................................................................... 11
Oil heaters.......................................................................................................................................... 11
Oil heater operation.......................................................................................................................... 11
Checking the oil level in the oil reservoir....................................................................................... 11
Start-up............................................................................................................................................... 12
Chiller operation................................................................................................................................ 12
Condenser water temperature control........................................................................................... 13
Operating log sheet.......................................................................................................................... 13
Operating inspections....................................................................................................................... 14
Need for maintenance or service.................................................................................................... 16
Stopping the system......................................................................................................................... 16
Prolonged shutdown......................................................................................................................... 16
System components description................................................................................................................ 17
Compressor........................................................................................................................................ 17
Capacity control................................................................................................................................. 17
Compressor lubrication system....................................................................................................... 17
Oil pump............................................................................................................................................. 18
Oil heater............................................................................................................................................ 20
Motor driveline.................................................................................................................................. 21
Heat exchangers................................................................................................................................ 21
Refrigerant flow control.................................................................................................................... 21
Optional service isolation valves..................................................................................................... 22
Optional hot gas bypass................................................................................................................... 22
OptiView™ Control Center................................................................................................................ 22
Solid state starter (optional)............................................................................................................ 22
Variable speed drive (optional)........................................................................................................ 23
Operational maintenance........................................................................................................................... 24
Oil return system............................................................................................................................... 24
Changing the dehydrator................................................................................................................. 24
The oil charge.................................................................................................................................... 25
Model YK (Style H), R-134a and R-513A 3

Oil charging procedure..................................................................................................................... 25
Troubleshooting........................................................................................................................................... 26
Maintenance................................................................................................................................................. 28
Renewal parts.................................................................................................................................... 28
Checking system for leaks................................................................................................................ 28
Conducting a system pressure test................................................................................................ 28
System evacuation............................................................................................................................ 31
Refrigerant charging......................................................................................................................... 36
Checking and trimming the refrigerant charge............................................................................ 38
Checking the refrigerant charge during unit shutdown.............................................................. 39
Handling refrigerant for dismantling and repairs........................................................................ 39
Megging the motor........................................................................................................................... 41
Compressor........................................................................................................................................ 44
Electrical controls.............................................................................................................................. 44
Preventive maintenance.............................................................................................................................. 45
Compressor........................................................................................................................................ 45
Compressor motor............................................................................................................................ 45
Greased bearings.............................................................................................................................. 45
Motor relubrication instruction....................................................................................................... 45
Leak testing........................................................................................................................................ 52
Evaporator and condenser............................................................................................................... 52
Oil return system............................................................................................................................... 52
Electrical controls.............................................................................................................................. 52
Maintenance inspections.................................................................................................................. 52
Unit conversion............................................................................................................................................ 55
Model YK (Style H), R-134a and R-513A4

General safety guidelines
Important: Read before proceeding.
This equipment is a relatively complicated apparatus. During rigging, installation, operation,
maintenance, or service, individuals may be exposed to certain components or conditions including,
but not limited to: heavy objects, refrigerants, materials under pressure, rotating components, and
both high and low voltage. Each of these items has the potential, if misused or handled improperly,
to cause bodily injury or death. It is the obligation and responsibility of rigging, installation, and
operating/service personnel to identify and recognize these inherent hazards, protect themselves,
and proceed safely in completing their tasks. Failure to comply with any of these requirements could
result in serious damage to the equipment and the property in which it is situated, as well as severe
personal injury or death to themselves and people at the site.
This document is intended for use by owner-authorized rigging, installation, and operating/service
personnel. It is expected that these individuals possess independent training that will enable them
to perform their assigned tasks properly and safely. It is essential that, prior to performing any
task on this equipment, this individual shall have read and understood the on-product labels, this
document and any referenced materials. This individual shall also be familiar with and comply
with all applicable industry and governmental standards and regulations pertaining to the task in
question.
Safety symbols
The following symbols are used in this document to alert the reader to specific situations:
DANGER
Indicates a possible hazardous situation which will result in death or serious injury if proper care is not
taken.
WARNING
Indicates a potentially hazardous situation which will result in possible injuries or damage to equipment
if proper care is not taken.
CAUTION
Identifies a hazard which could lead to damage to the machine, damage to other equipment and/or
environmental pollution if proper care is not taken or instructions and are not followed.
Note: Highlights additional information useful to the technician in completing the work being
performed properly.
5Model YK (Style H), R-134a and R-513A

WARNING
External wiring, unless specified as an optional connection in the manufacturer’s product line, is not
to be connected inside the control cabinet. Devices such as relays, switches, transducers and controls
and any external wiring must not be installed inside the micro panel. All wiring must be in accordance
with Johnson Controls’ published specifications and must be performed only by a qualified electrician.
Johnson Controls will NOT be responsible for damage/problems resulting from improper connections
to the controls or application of improper control signals. Failure to follow this warning will void the
manufacturer’s warranty and cause serious damage to property or personal injury.
Changeability of this document
In complying with Johnson Controls’ policy for continuous product improvement, the information
contained in this document is subject to change without notice. Johnson Controls makes no
commitment to update or provide current information automatically to the manual or product
owner. Updated manuals, if applicable, can be obtained by contacting the nearest Johnson
Controls Service office or accessing the Johnson Controls Knowledge Exchange website at https://
docs.johnsoncontrols.com/chillers/.
It is the responsibility of rigging, lifting, and operating/ service personnel to verify the applicability
of these documents to the equipment. If there is any question regarding the applicability of these
documents, rigging, lifting, and operating/service personnel should verify whether the equipment
has been modified and if current literature is available from the owner of the equipment prior to
performing any work on the chiller.
Revision notes
Revisions made to this document are indicated in the following table. These revisions are to
technical information, and any other changes in spelling, grammar, or formatting are not included.
Affected pages Description
41 Amended the section on Megging the motor.
54 Add the Smart sensor test item to the annual check list.
Associated literature
Manual description Form
Number
Operation - Variable Speed Drive - TM Model 160.00-O1
Operation and Maintenance - Solid State Starter (Mod B) 160.00-O2
Operation - Floor Mounted MVSSS 160.00-O5.1
Operation - Unit Mounted MVSSS 160.00-O7
Installation – YK Unit 160.76-N1
Installation and Reassembly - YK Unit 160.76-N3
Operation Manual – OptiView™ Control Center 160.76-O2
Wiring Diagram – Field Connections for YK Chiller (Style H) with OptiView™ Control
Center and Unit-Mounted SSS or Remote Medium Voltage SSS, Medium Voltage
VSD, or Medium Voltage EMS
160.76-PW1
Model YK (Style H), R-134a and R-513A6

Manual description Form
Number
Wiring Diagram – Field Connections for YK Chiller (Style H) with OptiView™ Control
Center and Remote Medium Voltage SSS 160.76-PW2
Wiring Diagram – Field Connections for YK Chiller (Style H) with OptiView™ Control
Center and Remote Medium Voltage VSD 160.76-PW3
Wiring Diagram – Field Control Modifications for YK Chiller (Style H) 160.76-PW4
Wiring Diagram – Model YK (Style H) with OptiView™ Control Center and Electro-
Mechanical Starter 160.76-PW5
Wiring Diagram – Model YK (Style H) with OptiView™ Control Center and SSS W/
Modbus, LV VSD W/Modbus 160.76-PW6
Wiring Diagram – Field Connections Model YK Chillers (Style H) with Low Voltage
Variable Speed Drive 160.76-PW7
Conditioned based maintenance
Traditional chiller maintenance is based upon assumed and generalized conditions. In lieu of
the traditional maintenance program, a Johnson Controls YORK Conditioned Based Maintenance
(CBM) program can be substituted. This CBM service plan is built around the specific needs for
the chiller, operating conditions, and annualized impact realized by the chiller. Your local Johnson
Controls Branch can propose a customized Planned Service Agreement that leverages real time
and historical data, delivering performance reporting, corrective actions required and data enabled
guidance for optimal operation and lifecycle assurance. The program will include fault detection
diagnostics, operation code statistics, performance based algorithms and advance rules based
rationale delivered by the Johnson Controls Connected Equipment Portal.
7Model YK (Style H), R-134a and R-513A

Nomenclature
Note: * Refer to YK Engineering Guide (Form 160.76-EG1) for shell, motor, and compressor
combinations.
Model YK (Style H), R-134a and R-513A8

Description of system and fundamentals of
operation
System operation description
The YORK Model YK Chiller is commonly applied to large air conditioning systems, but may be
used on other applications. The chiller consists of an open motor mounted to a compressor (with
integral speed increasing gears), condenser, evaporator and variable flow control.
The chiller is controlled by a modern state of the art Microcomputer Control Center that monitors
its operation. The Control Center is programmed by the operator to suit job specifications.
Automatic timed start-ups and shutdowns are also programmable to suit nighttime, weekends,
and holidays. The operating status, temperatures, pressures, and other information pertinent to
operation of the chiller are automatically displayed and read on a graphic display. Other displays
can be observed by pressing the keys as labeled on the Control Center. The chiller with the
OptiView Control Center is compatible with an electro-mechanical starter, YORK Solid State Starter
(optional), or Variable Speed Drive (optional).
In operation, a liquid (water or brine to be chilled) flows through the evaporator, where boiling
refrigerant absorbs heat from the liquid. The chilled liquid is then piped to fan coil units or other air
conditioning terminal units, where it flows through finned coils, absorbing heat from the air. The
warmed liquid is then returned to the chiller to complete the chilled liquid circuit.
Figure 1: Compressor pre-rotation vanes
The refrigerant vapor, which is produced by the boiling action in the evaporator, flows to the
compressor where the rotating impeller increases its pressure and temperature and discharges it
into the condenser. Water flowing through the condenser tubes absorbs heat from the refrigerant
vapor, causing it to condense. The condenser water is supplied to the chiller from an external
source, usually a cooling tower. The condensed refrigerant drains from the condenser into the
liquid return line, where the variable orifice meters the flow of liquid refrigerant to the evaporator
to complete the refrigerant circuit.
The major components of a chiller are selected to handle the refrigerant, which would be
evaporated at full load design conditions. However, most systems are called upon to deliver full
load capacity for only a relatively small part of the time the unit is in operation.
9Model YK (Style H), R-134a and R-513A

Capacity control
The major components of a chiller are selected for full load capacities, therefore capacity must be
controlled to maintain a constant chilled liquid temperature leaving the evaporator. Pre-rotation
vanes (PRV), located at the entrance to the compressor impeller, compensate for variation in load.
See Figure 1.
The position of these vanes is automatically controlled through a lever arm attached to an electric
motor located outside the compressor housing. The automatic adjustment of the vane position in
effect provides the performance of many different compressors to match various load conditions
from full load with vanes wide open to minimum load with vanes completely closed.
Figure 2: Refrigerant flow-through chiller (falling film evaporator)
Model YK (Style H), R-134a and R-513A10

System operating procedures
Oil heaters
If the oil heater is de-energized during a shutdown period, it must be energized for 12 hours before
starting compressor, or remove all oil and recharge compressor with new oil. See Oil charging
procedure.
Oil heater operation
The oil heater operation is controlled by the OptiView™ Control Center. The heater is turned on
and off to maintain the oil temperature differential to a value 50°F (27.8°C) above the condenser
saturation temperature. This target value is maintained by the control panel.
If the target value is greater than 160°F (71°C), the target defaults to 160°F (71°C). If the target
value is less than 110°F (43.3°C), it defaults to 110°F (43.3°C).
To prevent overheating of the oil in the event of a control center component failure, the oil heater
thermostat (1HTR) is set to open at 180°F (82°C).
Checking the oil level in the oil reservoir
Correct operating oil level: During operation, the oil level falls to the OPERATING RANGE identified
on the vertical oil level indicator label. See Figure 3.
Figure 3: Oil level indicator
• If the oil level during operation is in the OVER FULL region of the oil level indicator, remove oil
from the oil reservoir. This reduces the oil level to the OPERATING RANGE.
• If the oil level during operation is in the LOW OIL region of the oil level indicator, add oil to
the oil reservoir. See Oil charging procedure.
11Model YK (Style H), R-134a and R-513A

CAUTION
Comply with EPA and local regulations when removing or disposing of refrigeration system oil.
Start-up procedure
Pre-starting
Prior to starting the chiller, observe the Optiview™ Control Center – Operation Manual (160.76-O2).
Make sure the display reads SYSTEM READY TO START.
CAUTION
Vent any air from the chiller waterboxes prior to starting the water pumps. Failure to do so will result in
pass baffle damage.
Start-up
1. The Start/Stop control is operated via the Soft START button on the Home Screen. When the
user presses the green START button, a dialog box is displayed instructing the user to press
the ENTER button to start the chiller, or to press the CANCEL button to abort the start.
2. When the chiller is running, the Start button is replaced by a red SOFT STOP button. When
the user presses this button, a dialog box is displayed instructing the user to press the ENTER
button to stop the chiller, or the CANCEL button to abort the stop command. The Soft Stop
command drives the PRV closed and then shuts off the chiller.
For display messages and information pertaining to the operation refer to OptiView™ Control Center
– Operation Manual (160.76-O2).
Note: Any malfunctions that occur during STOP/RESET are also displayed.
Chiller operation
The unit capacity varies to maintain the leaving CHILLED LIQUID TEMPERATURE setpoint by the pre-
rotation vanes, which are modulated by an actuator under the control of the Microprocessor Board.
The vane control routine employs proportional plus derivative (rate) control action. A drop in chilled
liquid temperature causes the actuator to close the pre-rotation vanes to decrease chiller capacity.
When the chilled liquid temperature rises, the actuator opens the pre-rotation vanes to increase the
capacity of the chiller.
However, the current draw (amperes) by the compressor motor is also limited to FLA setpoint by
the microprocessor.
If the load continues to decrease, after the pre-rotation vanes are entirely closed, the chiller is shut
down by the Leaving Chilled Liquid – Low Temperature Control.
The coolant temperature inside any Johnson Controls supplied liquid-cooled motor starter must
be maintained above the dewpoint temperature in the equipment room to prevent condensing
water vapor inside the starter cabinet. Therefore, an additional temperature-controlled throttle
valve is needed in the flow path for the starter heat exchanger to regulate cooling above the
equipment room dewpoint for applications using cooling sources other than evaporative air-
Model YK (Style H), R-134a and R-513A12

exchange methods, such as wells, bodies of water, and chilled water. The temperature control
valve should be the type to open on increasing drive coolant temperature, fail-closed, and set for a
temperature above dewpoint. It can be requested as factory- supplied on a chiller order by special
quotation.
Condenser water temperature control
The YORK chiller is designed to use less power by taking advantage of lower than design
temperatures that are naturally produced by cooling towers throughout the operating year. Exact
control of condenser water such as a cooling tower bypass, is not necessary for most installations.
The minimum entering condenser water temperature for full and part load conditions is specified
in the chiller engineering guide, where:
• ECLT = Entering Condensing Liquid Temperature
• LCHLT = Leaving Chilled Liquid Temperature
• C Range = Condenser Leaving Liquid Temperature - Condenser Entering Liquid Temperature
at the load condition being calculated
At start-up, the entering condenser water temperature may be as much as 25°F (14°C) colder
than the standby return chilled water temperature. Cooling tower fan cycling normally provides
adequate control of the entering condenser water temperature on most installations.
Heat recovery chillers and chillers using optional head pressure control would use a signal provided
by the microprocessor to control main condenser bundle heat rejection or pressure, respectively.
Operating log sheet
A permanent daily record of system operating conditions (temperatures and pressures) recorded at
regular intervals throughout each 24 hour operating period should be kept.
An optional status printer is available for this purpose or Figure 4 shows a log sheet used by
Johnson Controls Personnel for recording test data on chiller systems. It is available from the
factory in pads of 50 sheets each under Form 160.54-MR1 and may be obtained through the nearest
Johnson Controls office. Automatic data logging is possible by connecting the optional printer and
programming the DATA LOGGER function.
An accurate record of readings serves as a valuable reference for operating the system. Readings
taken when a system is newly installed will establish normal conditions with which to compare later
readings.
For example, an increase in condenser approach temperature (condenser temperature minus
leaving condenser water temperature) may be an indication of dirty condenser tubes.
13Model YK (Style H), R-134a and R-513A

Figure 4: Liquid chiller log sheets
Note: These items can be printed by an electronic printer connected to the Microboard and
pressing the PRINT key on the keypad, or automatically using the Data Logger feature.
Operating inspections
By following a regular inspection using the display readings of the Microcomputer Control Center,
and maintenance procedure, the operator can avoid serious operating difficulty. The following list
of inspections and procedures should be used as a guide.
Daily
1. Check OptiView™ Control Center displays.
2. If the compressor is in operation, check the bearing oil pressure on the System screen. Also
check the oil level in the oil reservoir. Operating oil level should be operating range of oil
indicator. Drain or add oil if necessary.
3. Check entering and leaving condenser water pressure and temperatures for comparison with
job design conditions. Condenser water temperatures can be checked on the System screen.
4. Check the entering and leaving chilled liquid temperatures and evaporator pressure for
comparison with job design conditions on the System screen.
5. Check the condenser saturation temperature (based upon condenser pressure sensed by the
condenser transducer) on the System screen.
6. Check the compressor discharge temperature on the System screen. During normal
operation discharge temperature does not exceed 220°F (104°C).
7. Check the compressor motor current on the System screen.
8. Check for any signs of dirty or fouled condenser tubes. The temperature difference between
water leaving condenser and saturated condensing temperature should not exceed the
difference recorded for a new unit by more than 4°F (2.2°C).
Weekly
• Check the refrigerant charge (see Checking the refrigerant charge during unit shutdown).
Model YK (Style H), R-134a and R-513A14

Monthly
1. Leak check the entire chiller.
2. Check the oil return system operation.
3. Check the operation of the motor starter.
4. Check the sump heater and thermostat operation.
5. Check the three-phase voltage and current balance.
6. Verify the correct operation, setting, and calibration of safety controls.
7. Verify the condenser and evaporator water flows.
8. Perform a leak check and repair leaks as needed.
Annually (more often if necessary)
1. Chiller oil circuit:
a. Conduct an oil analysis and record the results.
b. Drain and replace the oil in the compressor oil sump. See Oil charging procedure. The
maximum period between oil changes is 5 years.
c. Replace the oil filter(s).
d. Replace the filter driers in the oil eductor circuit.
2. VSD or starter:
a. Check and tighten all electrical connections.
b. Change the VSD inhibitor in accordance with the 60.00-M12 instructions.
c. Clean the condenser/evaporator side of the VSD external heat exchanger.
d. Replace or clean the starter or drive air filters where applicable.
3. Evaporator and condenser:
a. Inspect and clean the water strainers.
b. Inspect and clean the tubes as required.
c. Inspect the end sheets.
4. Drive motor (see Motor relubrication instruction or refer to SI0305):
a. Clean the air passages and windings according to the manufacturer’s instructions.
b. Meg the motor windings. See for details.
c. Lubricate according to motor manufacturer recommendations.
d. Conduct vibration testing and record the results.
5. Compressor:
- Conduct vibration testing and record results.
6. Chiller systems:
a. Inspect and service all chiller system electrical components as necessary.
b. Perform refrigerant analysis.
15Model YK (Style H), R-134a and R-513A

Need for maintenance or service
If the system is malfunctioning in any manner or the unit is stopped by one of the safety controls,
consult Table 1 of this manual. After consulting this chart, if you are unable to make the proper
repairs or adjustments to start the compressor or the particular trouble continues to hinder the
performance of the unit, please call the nearest Johnson Controls District Office. Failure to report
constant troubles could damage the unit and increase the cost of repairs.
Stopping the system
The OptiView™ Control Center can be programmed to start and stop automatically (maximum, once
each day) whenever desired. Refer to the OptiView™ Control Center – Operation Manual (160.76-O2).
To stop the chiller, proceed as follows:
1. Push the soft shutdown key on the homescreen on the OptiView panel or rapid stop with
the COMPRESSOR STOP/RESET switch. The compressor stops automatically. The oil pump
continues to run for coastdown period. The oil pump then stops automatically.
2. Stop the chilled water pump (if not wired into the Microcomputer Control Center, in which
case it shuts off automatically simultaneously with the oil pump.). The actual water pump
contact operation is dependent upon the position of Microboard jumper J54.
3. Open the switch to the cooling tower fan motors, if used.
4. The compressor sump oil heater is energized when the unit is stopped.
Prolonged shutdown
If the chiller is to be shut down for an extended period of time (for example, over the winter
season), the following paragraphs outline the procedure to be followed:
1. Test all system joints for refrigerant leaks with a leak detector. If any leaks are found, they
should be repaired before allowing the system to stand for a long period of time. During long
idle periods, the tightness of the system should be checked periodically.
2. If freezing temperatures are encountered while the system is idle, carefully drain the cooling
water from the cooling tower, condenser, condenser pump, and the chilled water system-
chilled water pump and coils. Open the drains on the evaporator and condenser liquid heads
to ensure complete drainage. If a Variable Speed Drive, drain its cooling system. If Solid State
Starter equipped drain liquid from starter cooling loop.
3. If freezing temperatures are encountered for periods longer than a few days, the refrigerant
should be recovered to containers to prevent leakage from O-Ring joints.
4. On the SETUP Screen, disable the clock. This conserves the battery.
5. Open the main disconnect switches to the compressor motor, condenser water pump and
the chilled water pump. Open the 115 V circuit to the Control Center.
Model YK (Style H), R-134a and R-513A16

System components description
The YORK Model YK Centrifugal Liquid Chiller is completely factory-packaged including
evaporator, condenser, compressor, motor, lubrication system, OptiView™ Control Center, and all
interconnecting unit piping and wiring.
Compressor
The compressor is a single-stage centrifugal type powered by an open-drive electric motor.
The rotor assembly consists of a heat-treated alloy steel drive shaft and impeller shaft with a cast
aluminum, fully shrouded impeller. The impeller is designed for balanced thrust and is dynamically
balanced and over-speed tested. The inserted type journal and thrust bearings are fabricated of
aluminum alloy. Single helical gears with crowned teeth are designed so that more than one tooth
is in contact at all times. Gears are integrally assembled in the compressor rotor support and are
film lubricated. Each gear is individually mounted in its own journal and thrust bearings.
The open-drive compressor shaft seal is a double bellows cartridge style with ceramic internal
and atmospheric seal faces. The seal is oil-flooded at all times and is pressure-lubricated during
operation.
Capacity control
Pre-rotation vanes (PRV) modulate chiller capacity from 100% to as low as 15% of design for normal
air conditioning applications. Operation is by an external, electric PRV actuator which automatically
controls the vane position to maintain a constant leaving chilled liquid temperature.
Compressor lubrication system
The chiller lubrication system consists of the oil pump, oil filter, oil cooler and all interconnecting
oil piping and passages. There are main points within the compressor which must be supplied with
forced lubrication as follows:
1. Compressor drive shaft (low speed):
a. Shaft seal.
b. Front and rear journal bearings – one on each side of driving gear.
c. Low speed thrust bearing (forward and reverse).
2. Compressor driven shaft (high speed):
a. Forward and reverse high speed thrust bearing.
b. Two journal bearings.
3. Speed increasing gears:
- Meshing surfaces of drive and pinion gear teeth.
To provide the required amount of oil under the necessary pressure to properly lubricate these
parts, a motor driven submersible oil pump is located in a remote oil sump.
When you press the Compressor Start button on the Control Center, the oil pump immediately
energizes. After a 50 second pre-lube period, the compressor motor starts. The oil pump continues
to run during the entire operation of the compressor, and for 150 seconds during compressor
coastdown.
17Model YK (Style H), R-134a and R-513A

The submerged oil pump takes suction from the surrounding oil and discharges it to the oil cooler
where heat is rejected. The oil flows from the oil cooler to the oil filter. The oil leaves the filter and
flows to the emergency oil reservoir where it is distributed to the compressor bearings. The oil
lubricates the compressor rotating components and is returned to the oil sump.
There is an emergency oil reservoir located at the highest point in the lubrication system internally
in the compressor. It provides an oil supply to the various bearings and gears in the event of a
system shutdown due to power failure. The reservoir, located on the top of the compressor, allows
the oil to be distributed through the passages by gravity flow, thus providing necessary lubrication
during the compressor coastdown.
Oil pump
For normal operation, the oil pump should operate at all times during chiller operation.
On shutdown of the system for any reason, the oil pump operates and continues to run for 150
seconds. The system cannot restart during that time interval.
Figure 5: System components, front view
Callout Description Callout Description
1 Relief valves 5 Variable speed drive
2 Suction 6 Evaporator
3 OptiView control center 7 Variable speed oil pump control box
4 Compressor 8 Sight glass
Model YK (Style H), R-134a and R-513A18

Figure 6: System components, rear view
Callout Description Callout Description
1 Motor 5 Liquid line
2 Oil filter 6 Oil pump housing
3 Compressor 7 Condenser
4 Discharge line
19Model YK (Style H), R-134a and R-513A

Figure 7: Schematic drawing – (YK) Compressor lubrication system
Oil heater
During long idle periods, the oil in the compressor oil reservoir tends to absorb as much refrigerant
as it can hold, depending upon the temperature of the oil and the pressure in the reservoir. As
the oil temperature is lowered, the amount of refrigerant absorbed increases. If the quantity
of refrigerant in the oil becomes excessive, violent oil foaming results as the pressure within
the system is lowered on starting. This foaming is caused by refrigerant boiling out of the oil as
Model YK (Style H), R-134a and R-513A20