York MILLENNIUM YK Manual

OPERATING & MAINTENANCE Supersedes: Nothing Form 160.52-O1 (898)
MODEL YK (STYLE D)
R-134a (COOLING ONLY)
WITH MICROCOMPUTER CONTROL CENTER
PART #371-01200-010, 371-01200-011 & 371-01200-015
FOR ELECTRO-MECHANICAL STARTER,
SOLID STATE STARTER & VARIABLE SPEED DRIVE
WARNING
SYSTEM CONTAINS REFRIGERANT UNDER PRESSURE.
SERIOUS INJURY COULD RESULT IF PROPER PROCEDURES ARE NOT
FOLLOWED WHEN SERVICING SYSTEM. ALL SERVICE WORK SHALL
BE PERFORMED BY A QUALIFIED SERVICE TECHNICIAN IN ACCOR-
DANCE WITH YORK INSTALLATION/OPERATION MANUAL.
MILLENNIUM TM
CENTRIFUGAL LIQUID CHILLERS
28815A

2YORK INTERNATIONAL
TABLE OF CONTENTS
SECTION 1  Description of System and
Fundamentals of Operation......................................... 4
SECTION 2  MicroComputer Control Center ...................................... 6
SECTION 3  System Operating Procedures ..................................... 31
SECTION 4  System Component Description................................... 38
SECTION 5  Operational Maintenance ............................................. 43
SECTION 6  Trouble Shooting .......................................................... 45
SECTION 7  Maintenance ................................................................. 50
SECTION 8  Preventive Maintenance............................................... 59
Page
REFERENCE INSTRUCTIONS
DESCRIPTION FORM NO.
Solid State Starter  Operation & Maintenance 160.46-OM3.1
Variable Speed Drive  Operation 160.00-O1
Installation 160.52-N1
Wiring Diagram  Unit with Electro-Mechanical Starter 160.52-PW1
Wiring Diagram  Unit with Solid State Starter 160.52-PW2
Wiring Diagram  Unit with Variable Speed Drive 160.52-PW3

FORM 160.52-O1
3
YORK INTERNATIONAL
NOMENCLATURE
YK CB CB G4  CM D
DESIGN LEVEL (D)
POWER SUPPLY
 for 60 HZ
5 for 50 HZ
COMPRESSOR CODE
G4, H0, H1, H2, H3, H4, H5,
H6, H8, J1, J2, J3, J4
CONDENSER CODE
CB, CC, CD, DB, DC, DD, EB, EC, ED,
FB, FC, FD, GB, GC, GD, HB, HC, HD, JB, JC,
JD, TB, TC, TD, VB, VC, VD
COOLER CODE
CB, CC, CD, CE, DB, DC, DD, DE, FB, FC, FD,
GB, GC, GD, GF, GH, HB, HC, HF, HH, JF, JG,
JH, TF, TG, TH, VF, VH, WF, WH
MODEL
{MOTOR CODE:
60 HZ 50 HZ
CH CX 5CE 5CT
CJ CY 5CF 5CU
CK CZ 5CG 5CV
CL CA 5CH 5CW
CM CB 5CI 5CX
CN DA 5CJ 5DA
CP DB 5CK 5DB
CR DC 5CL 5DC
CS DD 5CM 5DD
CT DE 5CN 5DE
CU DF 5CO 5DF
CV DH 5CP 5DG
CW DJ 5CQ 5DH
5CR 5OJ
5CS

4YORK INTERNATIONAL
SECTION 1
DESCRIPTION OF SYSTEM AND FUNDAMENTALS OF OPERATION
FIG. 1  MODEL YK MILLENNIUM CHILLER
SYSTEMOPERATIONDESCRIPTION (See Fig. 2)
The YORK Model YK Millennium 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, cooler and vari-
able flow control.
The chiller is controlled by a modern state of the art
MicroComputer Control Center that monitors its opera-
tion. The Control Center is programmed by the opera-
tor to suit job specifications. Automatic timed start-ups
and shutdowns are also programmable to suit night-
time, weekends, and holidays. The operating status,
temperatures, pressures, and other information perti-
nent to operation of the chiller are automatically dis-
played and read on a 40 character alphanumeric mes-
sage display. Other displays can be observed by press-
ing the keys as labeled on the Control Center. The chiller
with the MicroComputer Control Center is applied 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 cooler, 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.
The refrigerant vapor, which is produced by the boiling
action in the cooler, flows to the compressor where the
rotating impeller increases its pressure and tempera-
ture and discharges it into the condenser. Water flow-
ing through the condenser tubes absorbs heat from
the refrigerant vapor, causing it to condense. The con-
denser water is supplied to the chiller from an external
source, usually a cooling tower. The condensed refrig-
erant drains from the condenser into the liquid return
line, where the variable orifice meters the flow of liquid
refrigerant to the cooler to complete the refrigerant
circuit.
The major components of a chiller are selected to
handle the refrigerant, which would be evaporated at
28815A
CONTROL
CENTER
COMPRESSOR
COOLER
CONDENSER
MOTOR

FORM 160.52-O1
5
YORK INTERNATIONAL
7619A(D)
DETAIL A  COMPRESSOR PREROTATION VANES
FIG. 2  REFRIGERANT FLOW-THRU CHILLER
PREROTATION VANES
(See Detail A)
SUCTION
COOLER
ELIMINATOR
OIL COOLER
LD00924
FLOW CONTROL
ORIFICE
SUB-COOLER
CONDENSER
DISCHARGE
BAFFLE
DISCHARGE
COMPRESSOR
full load design conditions. However, most systems will
be called upon to deliver full load capacity for only a
relatively small part of the time the unit is in operation.
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 leav-
ing the cooler. Prerotation vanes (PRV), located at the
entrance to the compressor impeller, compensate for
variation in load (See Fig. 2. Detail A).
The position of these vanes is automatically controlled
through a lever arm attached to an electric motor lo-
cated 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.

6YORK INTERNATIONAL
SECTION 2
MICROCOMPUTER CONTROL CENTER
LD00953
26879A
FIG. 3  MICROCOMPUTER CONTROL CENTER AND KEYPAD
NOTE: This instruction covers operation of chillers equipped with Electro-Mechanical or Solid State Starters. If
chiller is equipped with Variable Speed Drive, Form 160.00-O1 is to be used in conjunction with this manual.
WARNING
This equipment generates, uses and can radiate radio frequency energy and if not installed and used in
accordance with the instructions manual, may cause interference to radio communications. Operation of this
equipment in a residential area is likely to cause interference in which case the user at his own expense will
be required to take whatever action may be required to correct the interference.
Additionally, any electronic equipment can generate EMI (electromagnetic interference) which, depending
upon the installation and magnitude, may affect other electronic equipment. The amount of EMI generated is
determined by the source inductance, load inductance, and circuit impedances. Responsibility for assuring the
satisfactory operation of other equipment included in the same power source as the YORK equipment rests
solely with the user. YORK disclaims any liability resulting from any interference or for the correction thereof.

FORM 160.52-O1
7
YORK INTERNATIONAL
INTRODUCTION
The YORK MicroComputer Control Center is a micro-
processor based control system for R134a centrifugal
chillers. It controls the leaving chilled water tempera-
ture via pre-rotation vane control and has the ability to
limit motor current via control of the pre-rotation vanes.
Further, it is compatible with YORK Solid State Starter
(optional), Variable Speed Drive (optional), and elec-
tromechanical starter applications.
The Control Center can be equipped with an optional
Chinese language display, either as a field retrofit or
factory supplied option on new units. This display
mounts on the control center door, directly above the
standard display. Both the standard and Chinese dis-
play will be present, providing display messages simul-
taneously in both English and Chinese language. (The
Control Center must be configured for Chinese display
by a qualified service technician. Instructions are con-
tained in YORK service manual, Form 160.49-M2.)
A keypad mounted on the front of the Control Center
(see Fig. 3) allows the operator to display system oper-
ating parameters on a 40 character alphanumeric dis-
play that is part of the keypad. These readings are dis-
played via Display keypad as follows: (In the English
mode; temperatures in °F, pressures in PSIG) (in the
metric mode, temperatures in °C, Pressures in KPa).
 CHILLED LIQUID TEMPERATURES  LEAVING
AND RETURN
 REFRIGERANT PRESSURES  EVAPORATOR
AND CONDENSER
 DIFFERENTIAL OIL PRESSURE  PUMP SPEED
 CONDENSER LIQUID TEMPERATURES  OP-
TIONAL FIELD INSTALLED  LEAVING AND RE-
TURN
* HIGH SPEED THRUST POSITION  HIGH SPEED
THRUST OIL TEMPERATURE
 OPTIONS
 PRINT *
 HISTORY PRINT *
 MOTOR CURRENT IN % OF FULL LOAD AMPS
 SATURATION TEMPERATURES  EVAPORATOR
AND CONDENSER
 DISCHARGE TEMPERATURE
 OIL TEMPERATURE
 HIGH & LOW OIL PRESSURE TRANSDUCER
PRESSURE
 SOLID STATE STARTER MOTOR CURRENT /
VOLTS (When Supplied)
 CONDENSER REFRIGERANT LEVEL
The system setpoints (see Fig. 3) are operator entered
on the front control center Setpoints keypad. These
setpoints can also be displayed on the 40 character
alphanumeric display. The system setpoints are:
 CHILLED LIQUID TEMPERATURE (LCWT)
 % CURRENT LIMIT
 PULLDOWN DEMAND LIMIT
 CLOCK (TIME-OF-DAY)
 DAILY SCHEDULE (7 DAY TIME-CLOCK PRO-
GRAMMING)
 HOLIDAY
 REMOTE RESET TEMPERATURE RANGE
 DATA LOGGER
 CONDENSER REFRIGERANT LEVEL
The cause of all system shutdowns (safety or cycling)
is preserved (until the system is reset or restarts) in the
MicroComputers memory for subsequent viewing on
the keypad display. The operator is continually advised
of system operating conditions by various background
and warning messages. The keypad contains special
service keys for use by the service technician when
performing system troubleshooting.
The MicroComputer Control Center is designed to be
compatible with most Energy Management Systems
(EMS) in use today. The standard design allows for the
following EMS interface:
1. Remote Start
2. Remote Stop
3. Remote LCWT Setpoint (Pulse Width Modulated
signal)
4. Remote Current Limit Setpoint (Pulse Width Modu-
lated signal)
5. A Remote Mode Ready to Start Status Contacts
6. Safety Shutdown Status Contacts
7. Cycling Shutdown Status Contacts
As an enhancement to the standard EMS features, an
optional card file with plug-in printed circuit boards is
available. These optional cards will accept a remote
LCWT 0 to 10°F (0 to 5.5°C) or 0 to 20°F (0 to 11.1°C)
setpoint offset and/or remote current limit setpoint in-
terface from three user input choices.
1. 4-20mA
2. 0-10VDC
3. Contact Closures
* These keys provide a print-out when the customer connects a
compatible printer to the Micro Board RS-232 serial port.

8YORK INTERNATIONAL
CONTROL CENTER
CONTROL CENTER
The Control Center front panel layout consists of five
key groups, one switch and a 1 line by 40 character
alphanumeric vacuum fluorescent display: (see Fig.
3.)
CHARACTERISTIC DISPLAYThe alphanumeric
vacuum fluorescent display is located to the right of
the STATUS key. All messages, parameters, set points,
and data can be viewed at this location. The main com-
munications between the operator or service techni-
cian and the MicroComputer Control Center occurs on
this display.
DISPLAYProvide a direct readout of each monitored
parameter on the alphanumeric display.
ENTRYThese keys are used to enter the values for
the operator programmed setpoints. These keys are
used in conjunction with the Setpoint keys while in
PROGRAM mode.
SETPOINTSThese keys are used as follows:
1. To view each setpoint, in any mode, or
2. To select the individual setpoints that are pro-
grammed by the operator in PROGRAM mode only.
Pressing the appropriate key enables the operator to
program that setpoint pressing the Entry keys.
SERVICEIncluded in this group of keys are those
functions that are only relevant to servicing the chiller.
Typically, these keys would not be used for daily chiller
operation.
ACCESS CODEPermits operator to access the pro-
gram.
PROGRAMPermits operator to program the Control
Center.
MODEPermits operator to check what mode the
Control Center is presently in (LOCAL, REMOTE or
SERVICE).
1. Serviceallows manual PRV control with visual
display readout of PRV operation.
2. Localallows manual compressor start from the
COMPRESSOR switch on the Control Center front.
3. Programallows operator programming of system
setpoints.
4. Remoteallows remote start, remote stop of com-
pressor and remote reset of LCWT and % current
limit.
COMPRESSOR-START, RUN, STOP/RESET
SWITCHThis 3-position rocker switch is used to start
(except in REMOTE mode), stop/run/reset the system.
OPERATION
DISPLAYING SYSTEM PARAMETERS
The Display keys are used to display selected moni-
tored parameters as follows: (Refer to Fig. 3.)
 Press and release the appropriate Display key 
the message will be displayed for 2 seconds.
 or 
 Press and hold the appropriate Display key  the
message will be displayed and updated every 0.5
seconds until the Display key is released.
 or 
 Press and release appropriate Display key, then
press and release the DISPLAY HOLD key  the
message will be displayed and updated every 2 sec-
onds until the DISPLAY HOLD key is again pressed
and released, or 10 minutes have elapsed, which-
ever comes first.
NOTE: If the display actually displays Xs, then the
monitored parameter is out of normal operat-
ing range (refer to Fig. 4). If the English/Met-
ric jumper is installed on the Micro Board, all
temperatures are displayed in degrees Fahr-
enheit (°F) and all pressures are displayed in
pounds per sq. inch gauge (PSIG) except oil
pressure which is displayed in pounds per sq.
inch differential (PSID). If the English/Metric
jumper is not installed, all temperatures are
displayed in degrees Centigrade (°C) and all
pressures are displayed in Kilo-Pascals (kPa).

FORM 160.52-O1
9
YORK INTERNATIONAL
To Display CHILLED LIQUID TEMPERATURES:
Press CHILLED LIQUID TEMPS display key as de-
scribed on page 7 to produce the following alphanu-
meric display message:
CHILLED LEAVING = XXX.X°F, RETURN = XXX.X°F
To Display REFRIGERANT PRESSURE:
Use REFRIGERANT PRESSURE display key as de-
scribed on page 7 to produce the following alphanu-
meric display message:
EVAP = XXX.X PSIG; COND = XXX.X PSIG
To Display OIL PRESSURE:
Use OIL PRESSURE display key as described on page
7 to produce the following alphanumeric display mes-
sage:
OIL PRESSURE = XXXX.X PSID; SETP=XXXX.XPSID
The differential pressure displayed is the pressure dif-
ference between the high side oil pressure transducer
(output of oil filter) and the low side oil pressure trans-
ducer (compressor sump). Displayed value includes
offset pressure derived from auto-zeroing during
START SEQUENCE INITIATED. A qualified Service
Technician using procedure in Service Manual 160.49-
M2 has programmed (between 20 and 45 PSID) the oil
pressure setpoint (SETP). If either transducer is out-
of-range, XX.X is displayed. Oil pressure is calcu-
lated as follows:
______ PSID = (HOP  LP)  OFFSET PRESSURE
OFFSET PRESSURE: Pressure differential between
the HOP transducer and LOP transducer outputs dur-
ing a 3 second period beginning 10 seconds after the
start of START SEQUENCE INITIATED. During this
time, the transducers will be sensing the same pres-
sure and their outputs should indicate the same pres-
sure. However, due to accuracy tolerances in trans-
ducer design, differences can exist. Therefore, to com-
pensate for differences between transducers and as-
sure differential pressure sensing accuracy, the OFF-
SET PRESSURE is subtracted algebraically from the
differential pressure. The offset pressure calculation will
not be performed if either transducer is out-of-range.
The offset value will be taken as 0 PSI in this instance.
To Display OPTIONS:
This key is not used.
NO OPTIONS INSTALLED
is displayed when this key is pressed.
To Display SSS MOTOR CURRENT / VOLTS:
(Solid State Starter Applications Only)
If chiller is equipped with a YORK Solid State Starter,
use SSS MOTOR CURRENT / VOLTS key to display
3-phase compressor motor current and 3-phase Solid
State Starter input line voltage.
Continuously pressing this key will display the motor
current and line voltage alternately. When used with
the DISPLAY HOLD key, motor current and line volt-
age will alternately be displayed each time this key is
pressed. The messages are as follows:
A AMPS = XXXX; B AMPS = XXXX; C AMPS = XXXX
V A-B = XXXX; V B-C = XXXX; V C-A = XXXX
If chiller is not equipped with a Solid State Starter, this
key produces the following message:
SOLID STATE STARTER NOT INSTALLED
In PROGRAM mode, this key is used to display the
applicable line voltage range (200-208VAC, 220-
240VAC, 380VAC, 400VAC, 415VAC, 440-480VAC,
500-600VAC, Supply Voltage Range Disabled). The
correct line voltage range is programmed at the YORK
factory and is checked by the service technician at start-
up. For security reasons, a special access code is re-
DISPLAY
READS
CONDENSER PRESS. = < 6.8 PSIG, or > 300 PSIG XX.X PSIG
EVAPORATOR PRESS. = < 50 PSIG, or > 125 PSIG XX.X PSIG
EVAP. PRESS. (BRINE) = < 25 PSIG, or > 100 PSIG XX.X PSIG
HOP TRANSDUCER = < 59.1 PSIG, or > 314.9 PSIG XX.X PSIG
LOP TRANSDUCER = < 23.2 PSIG, or > 271.8 PSIG XX.X PSIG
DISCHARGE TEMP. = < 20.3°F; > 226.4°F XXX.X°F
OIL TEMP. = < 20.3°F; > 226.4°F XXX.X°F
LEAVING CONDENSER
WATER TEMP. = < 8.4°F; > 134.1°F XXX.X°F
ENTERING CONDENSER
WATER TEMP. = < 8.4°F; > 134.1°F XXX.X°F
LEAVING EVAPORATOR = < 0°F XX.X°F
WATER TEMP. = > 81.1°F XX.X°F
ENTERING EVAPORATOR = < .1°F XX.X°F
WATER TEMP. = > 93°F XX.X°F
FIG. 4  SYSTEM PARAMETERS  OUT OF
RANGE READINGS

10 YORK INTERNATIONAL
quired to program the line voltage range. The line volt-
age range is used to determine a low line voltage thresh-
old for cycling shutdown. Refer to System Setpoints
for Trip/Reset values.
To Display CONDENSER LIQUID TEMPERATURES:
Use CONDENSER LIQUID TEMPS display key as
described above to produce the following alphanumeric
display message:
COND LEAVING = XXX.X°F; RETURN = XXX.X°F
NOTE: If the condenser liquid thermistors are not con-
nected, or both thermistors are out of range,
the display will blank when this key is pressed.
To Initiate a PRINT to Printer:
Press the PRINT key to initiate a printout to an optional
printer. When the key is pressed,
PRINT ENABLE is displayed.
Refer to MicroComputer Control Center  System Sta-
tus Printers instruction, Form 160.49-N2 for details of
the optional printers.
To Display MOTOR CURRENT:
Press the % MOTOR CURRENT display key as de-
scribed above to display motor current as a percent of
Full Load Amps (FLA). The message is as follows:
MOTOR CURRENT = XXX% FLA
NOTE: Liquid-Cooled Solid State Starter Applications
 the % Motor Current displayed is the highest
of three line currents divided by the pro-
grammed chiller FLA value x 100%.
Electro-Mechanical Starter Applications  the
% Motor Current displayed is the highest of the
three line currents.
To Display OPERATING HOURS and STARTS
COUNTER:
Use the OPERATING HOURS key as described on
page 8, to produce the following message:
OPER. HOURS = XXXXX; START COUNTER = XXXXX
NOTE: The operating hours and starts counter can be
reset to zero. Refer to Programming the Mi-
croComputer Control Center, page 14. How-
ever, the purpose of the OPERATING HOURS
key is to display the total accumulated chiller
run time. Therefore, the operating hours should
not be arbitrarily reset.
SYSTEM SETPOINTS
The system setpoints may be programmed by the
system operator. The Setpoints keys are located on
the Control Center keypad (see Fig. 3). To program,
see Programming System Setpoints, page 14. The
following is a description of these setpoints (with the
English/Metric jumper installed on the Micro Board):
CHILLED LIQUID TEMPThis key displays the leav-
ing chilled water temperature (LCWT) setpoint in de-
grees Fahrenheit. If not programmed, the default value
is 45°F. See Programming System Setpoints, page
15).
NOTE: If an Energy Management System is interfaced
to the Control Center for the purpose of remote
LCWT setpoint reset, then the operator-pro-
grammed chilled liquid temperature will be the
base or lowest setpoint available to the Energy
Management System (EMS). This chilled liq-
uid temperature value must also be entered into
the EMS. Further, any subsequent change to
this value must also be entered into the EMS.
% CURRENT LIMITThis key displays the maximum
value of motor current permitted by its programmed
setting. The value is in terms of percent of Full Load
Amps (FLA). If not programmed, the default value is
100%. (See Programming System Setpoints, page
15.)
If chiller is equipped with a YORK Solid State Starter, the
system FLA is also displayed. This value is programmed
by the factory and should never be changed. The Micro
Board uses this value to calculate and display the % mo-
tor current parameter that is displayed when the % MO-
TOR CURRENT display key is pressed. Also, proper cur-
rent limit control depends on the correctly programmed
FLA value. For security reasons, a special access code
is required to program the FLA value. It should only be
changed by a service technician.
PULL DOWN DEMANDThis function is used to pro-
vide energy savings following the chiller start-up. This
key displays a programmable motor current limit and a
programmable period of time. Operation is as follows:
Whenever the system starts, the Pull Down Demand
Limit is maintained for the programmed time, then the
current limit control returns to % current limit setpoint.

FORM 160.52-O1
11
YORK INTERNATIONAL
LOW / HIGH LINE VOLTAGE TRIP / RESET VALUES
COMPRESSOR LOW LINE VOLTAGE HIGH LINE VOLTAGE
MOTOR OPERATING POINT OPERATING POINT
SUPPLY VOLTAGE CUTOUT-(V) CUTIN-(V) CUTOUT-(V) CUTIN-(V)
RANGE  (V) (ON FALL) (ON RISE) (ON RISE) (ON FALL)
380 305 331 415 414
400 320 349 436 435
415 335 362 454 453
440-480 370 400 524 523
550-600 460 502 655 654
Supply Voltage NONE 0 NONE 0
Range Disabled
The maximum permitted motor current is in terms of %
FLA. The duration of time that the current is limited is in
terms of minutes (to a maximum of 255). If not pro-
grammed, the default value is 100% FLA for 00 min-
utes. (See Programming Systems Setpoints, page 16.)
Thus, no pull down demand limit is imposed following
system start, and the % current limit setpoint is used.
CLOCKThis key displays the day of the week, time
of day and calendar date. If not programmed, the de-
fault value is SUNDAY 12:00 AM 1/1/92 .
(See Programming System Setpoints, page 16.)
DAILY SCHEDULEThis key displays the pro-
grammed daily start and stop times, from Sunday thru
Saturday plus Holiday. If desired, the Control Center
can be programmed to automatically start and stop the
chiller as desired. This schedule will repeat on a 7-day
calendar basis. If the Daily Schedule is not pro-
grammed, the default value is 00:00 AM start and stop
times for all days of the week and the holiday. (Note
that the system will not automatically start and stop on
a daily basis with these default values because 00:00
is an Impossible time for the Micro Board. See Pro-
gramming System Setpoints, page 17.) Finally, one or
more days in the week can be designated as a holiday
(see description under HOLIDAY setpoint) and the
Control Center can be programmed (usually Daily
Schedule setpoint) to automatically start and stop the
chiller on those days so designated. The operator can
override the time clock at any time using the COM-
PRESSOR switch.
Note that if only a start time is entered for a particular
day, the compressor will not automatically stop until a
scheduled stop time is encountered on a subsequent
day.
HOLIDAYThis key indicates which days in the up-
coming week are holidays. On those designated days,
the chiller will automatically start and stop via the holi-
day start and stop times programmed in the DAILY
SCHEDULE setpoint. It will do this one time only and
the following week will revert to the normal daily sched-
ule for that day.
REMOTE / RESET TEMP RANGEThis key displays
the maximum offset of remote LCWT setpoint reset.
This offset is either 10° or 20°F (5.5° or 11.1°C) as pro-
grammed. When in the REMOTE mode, this value is
added to the operator programmed CHILLED LIQUID
TEMP setpoint and the sum equals the temperature
range in which the LCWT can be reset. For example, if
the operator programmed CHILLED LIQUID TEMP
setpoint is programmed with a value of 10°F (5.5°C),
then the CHILLED LIQUID TEMP setpoint can be re-
motely reset over a range of 46°F to 56°F (46 + 10 =
56) (7.7° to 13.3°C). If not programmed, the default
value for this parameter is 20°F (11.1°C).
For additional information on remote LCWT reset, re-
fer to Form 160.49-PW13.
NOTE: If an Energy Management System is interfaced
to the Control Center for the purpose of remote
LCWT setpoint reset, then the operator pro-
grammed REMOTE RESET TEMP RANGE
value determines the maximum value of tem-
perature reset controlled by the Energy Man-
agement System.
DATA LOGGERThis key is used when an optional
printer is connected to the MicroComputer Control
Center. Refer to Form 160.49-N2 for operation instruc-
tions.
SSS MOTOR CURRENT/VOLTSThis key is used on
Solid State Starter applications only. Although this is a
display key, it is used to program the applicable AC
power line voltage range (380VAC, 400VAC, 415VAC,
440-480VAC, 550-600VAC). The MicroComputer Con-
trol Center uses this entry to determine the under-volt-
age and overvoltage shutdown threshold. For each
line voltage category, there is an undervoltage and ov-
ervoltage shutdown threshold. If the AC power line volt-
age exceeds these thresholds for 20 continuous sec-
onds, the chiller shuts down and displays
MON 10:00 AM LOW LINE VOLTAGE
 or 
MON 10:00 AM HIGH LINE VOLTAGE
This overvoltage and undervoltage protection can be
disabled. Refer to chart below:
For security reasons, a special access code is required
to program the supply voltage range. The supply volt-
age range is programmed at the factory and should
only be changed by a service technician.

12 YORK INTERNATIONAL
DISPLAYING SYSTEM SETPOINTS
The currently programmed Setpoint values can be
viewed at any time (see page 22) in SERVICE, LO-
CAL or REMOTE operating mode as follows:
 Press and release the appropriate Setpoint key 
the message will be displayed for 2 seconds.
 or 
 Press and hold the appropriate Setpoint key  the
message will be displayed as long as the key is
pressed.
 or 
 Press and release the appropriate Setpoint key,
then press and release the DISPLAY HOLD key.
The message will be displayed until the DISPLAY
HOLD key is again pressed and released, or 10
minutes have elapsed, whichever comes first.
To Display CHILLED LIQUID TEMP Setpoint:
Use CHILLED LIQUID TEMP setpoint key as described
on page 10 to produce the following message:
LEAVING SETPOINT = XX.X °F
NOTE: The value displayed is the actual LCWT set-
point. For example, the value displayed in LO-
CAL or PROGRAM modes is that which is
operator programmed. The value displayed in
the REMOTE mode is that base setpoint with
added temperature reset by an Energy Man-
agement System, via remote LCWT setpoint
(PWM signal) if a remote reset signal was re-
ceived within 30 minutes.
To Display % CURRENT LIMIT Setpoint:
Use % CURRENT LIMIT setpoint key as described
above to produce the following message:
CURRENT LIMIT = XXX % FLA
NOTE: The value displayed is the actual % current limit
setpoint. For example, the value displayed in
LOCAL or PROGRAM mode is that which is
operator programmed. The value displayed in
the REMOTE mode is that which has been pro-
grammed by the Energy Management System
via the remote current limit setpoint input.
If chiller is equipped with a YORK Solid State Starter,
the message is:
CURRENT LIMIT = XXX % FLA; *MTR CUR = 000 FLA
NOTE: On Solid State Starter applications, this value
is programmed at the YORK factory. A special
access code is required.
To Display PULL DOWN DEMAND Setpoint:
Use PULL DOWN DEMAND setpoint key as described
on page 10 to produce the following message:
SETPOINT = XXX MIN @ XX % FLA XXX MIN LEFT
To Display CLOCK Setpoint (Time of Day):
Use CLOCK setpoint key as described above to pro-
duce the following message:
TODAY IS DAY XX:XX AM/PM 1/1/92
To Display DAILY SCHEDULE Setpoints:
 Press and hold the DAILY SCHEDULE setpoint key.
The chiller start and stop times for each day of the
week are sequentially displayed, beginning with
Sunday and ending with Holiday. The display will
continuously scroll until the DAILY SCHEDULE key
is released.
 or 
 Press and release the DAILY SCHEDULE setpoint
key. Then press and release the DISPLAY HOLD
key. The chiller start and stop times for each day of
the week are sequentially displayed beginning with
Sunday and ending with Holiday. The display will
continuously scroll until the DISPLAY HOLD key is
again pressed and released, or 10 minutes have
elapsed, whichever comes first.
The display message for DAILY SCHEDULE will scroll
in the following sequence:
SUN START = 08:30 AM STOP = 06:00 PM
MON START = 05:00 AM STOP = 07:00 PM
TUE START = 05:00 AM STOP = 07:00 PM
WED START = 05:00 AM STOP = 07:00 PM
THU START = 05:00 AM STOP = 07:00 PM

FORM 160.52-O1
13
YORK INTERNATIONAL
FRI START = 05:00 AM STOP = 07:00 PM
SAT START = 05:00 AM STOP = 01:00 PM
HOL START = 00:00 AM STOP = 00:00 PM
To Display HOLIDAY Setpoints:
Use HOLIDAY setpoint key as described in the begin-
ning of this section to produce the following message:
S_ M_ T_ W_ T_ F_ S_ HOLIDAY NOTED BY *
NOTE: On the days that are designated by an *, the
chiller will automatically start and stop per the
holiday schedule established in DAILY
SCHEDULE setpoints.
To Display REMOTERESETTEMPRANGE Setpoint:
Use REMOTERESETTEMPRANGE setpoint key as
described above to produce the following message:
REMOTE RESET TEMP RANGE = 10°F
 or 
REMOTE RESET TEMP RANGE = 20°F
To DisplayDATA LOGGER setpoints:
Refer to YORK, Form 160.49-N2 for operation of this
key.
To Display UNDERVOLTAGE setpoints:
(Solid State Starter Applications Only)
Press SSS MOTOR CURRENT/VOLTS key in PRO-
GRAM mode to display the selected voltage range. One
of the following messages will be displayed.
SUPPLY VOLTAGE RANGE 380
 or 
SUPPLY VOLTAGE RANGE 400
 or 
SUPPLY VOLTAGE RANGE 415
 or 
SUPPLY VOLTAGE RANGE 440-480
 or 
SUPPLY VOLTAGE RANGE 550-600
 or 
SUPPLY VOLTAGE RANGE DISABLED
A special access code is required to program the Sup-
ply Voltage Range. The Supply Voltage Range is pro-
grammed at the factory and checked at system start-
up. (Note to service technician: Refer to programming
instructions in Service Instruction, Form 160.49-M2.)

14 YORK INTERNATIONAL
PROGRAMMING
THE MICROCOMPUTER CONTROL CENTER
FIG. 5  KEYPAD  PROGRAMMING SYSTEM
SETPOINTS
LD00954
PROGRAMMING SYSTEM SETPOINTS
The system setpoints can be entered at any time . . . .
even when the system is running. Proceed as follows
to enter system setpoints. (Refer to Fig. 5.)
1. Press ACCESS CODE key.
2. ENTER VALID ACCESS CODE _ _ _ _ is displayed.
3. Using ENTRY keys, enter 9 6 7 5.
4. As each digit is entered, the characters Y O R K
are displayed.
NOTE: If digits other than 9 6 7 5 are entered,
YORKis still displayed.
NOTE: For ease in remembering the code, note
that the lettersYORKcorrespond to the
digits 9675on a telephone dial.
5. Press ENTER key.
NOTE: If digits other than 9675 were entered in
step No. 4, INVALID ACCESS CODE is dis-
played when the ENTER key is pressed. If
this occurs, enter the correct access code
(9675) and proceed.
6. ACCESS TO PROGRAM KEY AUTHORIZED is displayed.
NOTE: Unless terminated by pressing the AC-
CESS CODE key again, the operator will
have access to the PROGRAM key for 10
minutes. When 10 minutes have elapsed,
access to PROGRAM key will be automati-
cally disabled and the operator must return
to step No. 1 to gain access.
7. Press PROGRAM key.
8. PROGRAM MODE, SELECT SETPOINT is displayed.
9. Enter setpoints as detailed below. If you make a
mistake when entering a value, press CANCEL key
and then ENTER key. The display will revert to the
default values and the cursor will return to the first
changeable digit. You can then proceed to enter the
correct values. If the entered value exceeds accept-
able limits, OUT OF RANGE  TRY AGAIN!
message will be displayed for 2 seconds, then the
PROGRAM MODE, SELECT SETPOINT message will
reappear.
10.When all the desired setpoints have been entered,
press the ACCESS CODE key to exit PROGRAM
mode and terminate access to PROGRAM mode.
ACCESS TO PROGRAM MODE DISABLED is displayed.
The Control Center will automatically return to LO-
CAL, REMOTE or SERVICE mode . . . . whichever
was last selected.

FORM 160.52-O1
15
YORK INTERNATIONAL
FIG. 6  KEYPAD  PROGRAMMING LEAVING
CHILLED WATER TEMP SETPOINT
FIG. 7  KEYPAD  PROGRAMMING % CURRENT
LIMIT SETPOINT
LD00955
LD00956
To enter CHILLED LIQUID TEMP Setpoint: (Refer to
Fig. 6.)
1. Press and release CHILLEDLIQUIDTEMP setpoint
key. The following program prompt message will be
displayed:
LEAVING SETPOINT = XX.X °F (BASE)
(BASE) refers to the base or lowest setpoint avail-
able to an Energy Management System. If any En-
ergy Management System is applied, this value must
be entered into the Energy Management System.
Refer to previous explanation or REMOTE/RESET
TEMP RANGE, page 11.
2. Use ENTRY keys to enter desired value.
3. Press and release ENTER key.
PROGRAM MODE, SELECT SETPOINT
message is displayed.
To Enter % CURRENT LIMIT Setpoint:
(Electro-Mechanical Starter, refer to Fig. 7)
1. Press and release % CURRENT LIMIT setpoint key.
The following program prompt message is displayed:
CURRENT LIMIT = XXX% FLA
2. Use ENTRY keys to enter desired value.
3. Press and release ENTER key.
PROGRAM MODE, SELECT SETPOINT
message is displayed.
(Solid State Starter, refer to Fig. 7)
1. Press and release % CURRENT LIMIT setpoint key.
The following program prompt message is displayed:
CURRENT LIMIT = XXX% FLA; MTR CUR = _ _ _ FLA
2. Use ENTRY keys to enter desired value.
NOTE: Motor Current FLA value is entered by
YORK factory and checked at system start-
up. It cannot be changed without special
access code. (Note to service technician:
refer to Programming Instructions in Ser-
vice instruction, Form 160.49-M2.
3. Press and release ENTER key.
PROGRAM MODE, SELECT SETPOINT
message is displayed.

16 YORK INTERNATIONAL
FIG. 8  KEYPAD  PROGRAMMING PULL DOWN
DEMAND SETPOINT
FIG. 9  KEYPAD  PROGRAMMING CLOCK
SETPOINT
LD00957
LD00958
To Enter PULL DOWN DEMAND Setpoint:
(Refer to Fig. 8.)
1. Press and release PULL DOWN DEMAND setpoint
key. The following program prompt message is dis-
played:
SETPOINT = XXX MIN @ XXX % FLA, XXX MIN LEFT
2. Use Entry keys to enter desired values. For expla-
nation, see PULL DOWN DEMAND, page 12. Note
that XX min left is not an operator entered value.
3. Press and release ENTER key.
PROGRAM MODE, SELECT SETPOINT
message is displayed.
To Enter CLOCK Setpoint: (Refer to Fig. 9.)
1. Assure Micro Board Program jumper J57 is in
CLKON position.
2. Press and release CLOCK setpoint key. The follow-
ing program prompt message is displayed:
TODAY IS MON 10:30 PM 1/1/92
3. Press ADVANCE DAY / SCROLL key until the pro-
gram per day of week appears on the display.
4. Use Entry keys to enter proper time of day.
5. Press AM/PM key to change the AM to PM or vice
versa.
6. Use Entry keys to enter proper calendar date,
(MONTH/DAY/YR). If month and day are single digit
entries, precede the entry with 0. For example,
02/04/98.
7. Press and release ENTER key.
PROGRAM MODE, SELECT SETPOINT
message is displayed.

FORM 160.52-O1
17
YORK INTERNATIONAL
FIG. 10  KEYPAD  PROGRAMMING DAILY
SCHEDULE SETPOINT
LD00959
To Enter DAILY SCHEDULE Setpoint:
(Refer to Fig. 10.)
1. Press and release DAILY SCHEDULE setpoint key.
The following prompt message is displayed:
SUN START = XX:XX AM, STOP = XX:XX AM
2. If the displayed start and stop time is not the desired
schedule, enter the desired start and stop times as
follows:
a. If you do not want the chiller to automatically start
and stop on this day, press CANCEL key.
b. Use the Entry keys to enter desired hours and
minutes start time.
c. If necessary, press the AM/PM key to change
AM to PM or vice versa.
d. Use the Entry keys to enter desired hours and
minutes stop time.
e. If necessary, press the AM/PM key to change
AM to PM or vice versa.
3. Press and release ADVANCE DAY/SCROLL key.
The following prompt message is displayed:
MON START = XX:XX AM, STOP = XX:XX AM
4. Enter the desired start and stop time per Step 2.
5. Press and release ADVANCE DAY/SCROLL key.
The following prompt message is displayed:
REPEAT MON SCHEDULE MON-FRI? YES = 1; NO = 0
a. If you press the 1 Entry key, Mondays start and
stop time will be automatically entered for Tues-
day through Friday.
 or 
b. If you press the 0 Entry key, Tuesday through
Friday can be programmed with different start and
stop times.
6. Use the ADVANCE DAY / SCROLL key with proce-
dure in Step 2. To enter start and stop times for re-
mainder of the week plus a holiday schedule if re-
quired.
7. Press the ENTER key.
PROGRAM MODE, SELECT SETPOINT is displayed.

18 YORK INTERNATIONAL
FIG. 11  KEYPAD  PROGRAMMING HOLIDAY
SETPOINT
FIG. 12  KEYPAD  PROGRAMMING REMOTE
RESET TEMP RANGE
LD00961
LD00962
To Enter HOLIDAY Setpoint: (Refer to Fig. 11.)
1. Press and release HOLIDAY setpoint key. The fol-
lowing program prompt message is displayed:
S_ M_ T_ W_ T_ F_ S_ HOLIDAY NOTED BY *
2. Press and release ADVANCE DAY/SCROLL key to
move cursor to the day that you wish to designate
as a holiday.
3. Press and release * entry key. An * will appear next
to the selected day.
4. After you have placed an * next to each of the days
that you wish to designate a holiday, press ENTER
key PROGRAM MODE, SELECT SETPOINT
message is displayed.
To cancel all of the designated holidays: perform
Step 1, press CANCEL key, and then press ENTER
key.
PROGRAM MODE, SELECT SETPOINT
message is displayed.
To cancel one of the designated holidays: perform
Step 1, press ADVANCE DAY / SCROLL key until
the cursor appears to the right of the desired day,
press the * key, then press the ENTER key.
To Enter REMOTE/ RESET TEMP RANGE Setpoint:
(Refer to Fig. 12.)
1. Press and release REMOTE/RESETTEMPRANGE
setpoint key. The following program prompt message
is displayed:
REMOTE TEMP SETPOINT RANGE = XX °F
2. Use Entry keys desired value (10 or 20).
3. Press and release ENTER key.
PROGRAM MODE, SELECT SETPOINT
message is displayed.
To Enter DATA LOGGER Setpoint:
Refer to Form 160.49-N2 for operation of this key.

FORM 160.52-O1
19
YORK INTERNATIONAL
The Service keys are provided for the service techni-
cians use when performing routine maintenance or
when troubleshooting the system. The WARNING RE-
SET and PRE-ROTATION VANES keys are enabled
in SERVICE mode only. The remainder of the Service
keys are enabled in SERVICE, LOCAL or REMOTE
mode.
PRE-ROTATION VANES KEYS
PRE-ROTATION VANES/REFRIGERANT LEVEL
CONTROL/MANUAL SPEED CONTROL  The pre-ro-
tation vanes keys can be used to manually control the
refrigerant level variable orifice, manually control the
oil pump speed or manually control the pre-rotation
vanes. The procedure to select either manual vane,
manual oil pump speed or manual variable orifice con-
trol is contained in Special Setpoints and Program-
ming Procedures section of Service manual, Form
160.49-M2 and must be performed by a qualified ser-
vice technician only.
1. Manual Vane Control:
OPENPress and release this key to drive the pre-
rotation vanes open. If the chiller is running,
SYSTEM RUN  VANES OPENING is displayed. If chiller is
not running, SYS READY TO START  VANES OPENING is
displayed. The vanes will continue to open until the
CLOSE, HOLD, or AUTO (if temperature error requires
it) keys are pressed and released.
FIG. 13  KEYPAD  SERVICE KEYS LOCATION
SERVICE KEYS
LD00963
HOLDPress and release this key to hold the pre-
rotation vanes in their present position. If the chiller is
running, SYSTEM RUN  VANES HOLDING is displayed.
If chiller is not running,
SYS READY TO START  VANES HOLDING is displayed.
The vanes will remain stationary until the OPEN, HOLD,
or AUTO keys are pressed and released.
CLOSEPress and release this key to drive the pre-
rotation vanes closed. If the chiller is running,
SYSTEM RUN  VANES CLOSING is displayed. If chiller is
not running, SYS READY TO START  VANES CLOSING is
displayed. When the vanes are full closed,
SYS READY TO START  VANES CLOSED is displayed.
The vanes will continue to close until the OPEN, HOLD,
or AUTO keys are pressed.
AUTOPress and release this key to put the pre-rota-
tion vanes under LCWT control as long as the current
limit setpoint is not reached, which causes the current
limit function to override the LCWT control. If system is
running, SYSTEM RUN  AUTO VANES is displayed. The
actual opening and closing of the vanes is indicated on
the display. When the vanes are opening,
SYSTEM RUN  VANES OPENING is displayed. If the vanes
are closing, SYSTEM RUN  VANES CLOSING is displayed.
Whenever the Control Center is in LOCAL, REMOTE
or PROGRAM mode, the vane control circuitry is auto-
matically placed in AUTO mode and the vanes oper-
ate to control the leaving chilled water temperature to
the programmed setpoint.

20 YORK INTERNATIONAL
Manual Refrigerant Level Control:
OPENPress and release this key to drive the refrig-
erant level control valve open. If the chiller is running,
SYSTEM RUN  LEVEL VALVE OPENING is displayed. If
chiller is not running,
SYS READY TO START  LEVEL VALVE OPENING is dis-
played. The refrigerant level control valve will continue
to open until the CLOSE, HOLD, or AUTO keys are
pressed and released.
HOLDPress and release this key to hold the refrig-
erant level control valve in its present position. If the
chiller is running, SYSTEM RUN  LEVEL VALVE HOLDING
is displayed. If chiller is not running,
SYS READY TO START  LEVEL VALVE HOLDING is displayed.
The refrigerant level control valve will remain station-
ary until the OPEN, HOLD, or AUTO keys are pressed
and released.
CLOSEPress and release this key to drive the re-
frigerant level control valve closed. If the chiller is run-
ning,
SYSTEM RUN  LEVEL VALVE CLOSING is displayed. If
chiller is not running,
SYS READY TO START  LEVEL VALVE CLOSING is displayed.
When the refrigerant level control valve is fully closed,
SYS READY TO START  LEVEL CLOSED is displayed. The
refrigerant level control valve will continue to close un-
til the OPEN, HOLD, or AUTO keys are pressed.
AUTOPress and release this key to return the refrig-
erant level control valve to automatic operation.
Manual Oil Pump Speed Control:
OPENPress and release this key with manual op-
eration of the oil pump will increase the VSD oil pump
speed by .5Hz.
CLOSEPress and release this key with manual op-
eration of the oil pump will decrease the VSD oil pump
speed by .5Hz.
HOLDPress and release this key will allow the VSD
oil pump to be driven to a specific pre-determined fre-
quency.
AUTOPress and release this key to return VSD oil
pump to automatic operation.
OTHER SERVICE KEYS
WARNING RESETPress and release this key to re-
set any WARNING or STATUS message that can
be reset with this key, unless the condition still exists.
To reset any cycling or warning message, place the
Control Center in SERVICE mode and press WARN-
ING RESET key. To reset any safety shutdown mes-
sage, press WARNING RESET key in SERVICE mode
with the COMPRESSOR switch in the STOP/RESET
position.
MANUAL OIL PUMPThis key is operational in any
mode. Press and release this key to run the oil pump.
Press and release the key again to stop the oil pump.
A 10-minute maximum is imposed on the running of
the oil pump (i.e. the oil pump will automatically shut
off after 10 minutes). If a longer running time is de-
sired, the key must be pressed again. The manual oil
pump feature is disabled during START SEQUENCE
INITIALIZED to allow for auto-zeroing of oil pressure
transducers.
DISPLAY DATAThis key is operational in any three
of the Control Center modes of operation (SERVICE,
LOCAL or REMOTE). It is used to display certain sys-
tem operating parameters that are relevant to trouble-
shooting the chiller system.
Press and the DISPLAY DATA key. The following mes-
sages will sequentially scroll on the display. Each mes-
sage will be displayed for 2 seconds.
NO. 1 
MANUAL VANE OPERATION ALLOWED  Displayed when
the PRE-ROTATION VANES service keys have been
selected for manual VANE control. This allows these
keys to manually control the vanes in Service mode.
The procedure to select manual vanes control is in Ser-
vice manual, Form 160.49-M3 and should be performed
only by a qualified service technician.
 or 
NO. 1 
MANUAL LEVEL CONTROL ALLOWED  Displayed when
the PRE-ROTATION VANES keys have been selected
for manual REFRIGERANT LEVEL control. This allows
these keys to manually control the refrigerant level con-
trol variable orifice in Service mode. When manual re-
frigerant level control is selected, the pre-rotation vanes
Service keys cannot be used to control the vanes. The
procedure to select manual refrigerant level control is
in Service manual, Form 160.49-M3 and should be
performed only by a qualified service technician.
or
NO.1 
MANUAL OIL PUMP SPEED CONTROL ALLOWED  Displayed
when the PRE-ROTATION VANES keys have been
selected for manual VSD OIL PUMP SPEED control.
This allows these keys to manually control the VSD oil
pump speed during manual oil pump operation in Ser-
vice mode. When manual oil pump speed control is
selected, the pre-rotation vanes Service keys cannot
be used to control the vanes. The procedure to select