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FORM 160.54-M1
ISSUE DATE: 10/25/2019
SECTION 33 - SYSTEM CALIBRATION, SERVICE SETPOINTS, AND RESET PROCEDURES
JCI COMPANY CONFIDENTIAL
JOHNSON CONTROLS
sage will clear and the PRV inhibit is removed when
the pressure decreases to 5 psig below the programmed
value. Proceed as follows to enter this value:
1. At the keypad, log in at SERVICE access level
using access code 1 3 8 0.
2. Select CONDENSER Screen.
3. On the CONDENSER Screen, press HIGH PRES-
SURE WARNING THRESHOLD key.
4. Using numeric keypad keys, enter desired value.
5. Press ENTER (
) key.
BRINE LOW EVAPORATOR PRESSURE
CUTOUT
On Brine cooling applications, the LOW EVAPORA-
TOR PRESSURE safety shutdown threshold is pro-
grammable over the range of 25.0 to 54.3 psig (Default
54.3 psig) for R22 Refrigerant and 6.0 to 25.0 psig
(Default 25.0 psig) for R-134a Refrigerant. The actual
percentage of Brine solution determines this threshold.
It is calculated at the YORK factory and programmed
at the time of manufacture. If the BRAM memory de-
vice on the microboard is replaced, the threshold will
have to be programmed in the field. The threshold is
logged on an adhesive label attached to the inside of
the OptiView Control Center door. Proceed as follows
to enter this value:
1. At the keypad, log in at SERVICE access level
using access code 1 3 8 0.
2. Select EVAPORATOR Screen.
3. On the EVAPORATOR Screen, press the BRINE
LOW EVAPORATOR CUTOUT key.
4. Using numeric keypad keys, enter desired value.
5. Press ENTER (
) key.
LEAVING CHILLED LIQUID TEMPERATURE
CONTROL SENSITIVITY
This setpoint adjusts the Leaving Chilled Liquid Tem-
perature control sensitivity. It determines the magni-
tude of Pre-rotation Vanes (PRV) response to correct
the error between the Leaving Chilled Liquid Tempera-
ture setpoint and the actual liquid temperature leaving
the chiller. There are three selections as follows:
Normal -
Provides standard control operation. PRV
open and close pulses are standard durations
for any given error. Longest allowed pulse
is 18 seconds in duration. This selection will
provide proper operation in most applications.
50% - Provides less sensitivity than the NORMAL
selection. The longest allowed open or close
pulse is limited to 50% of the maximum al-
lowed with the NORMAL selection. This
provides less overall PRV movement than
the NORMAL selection. This selection will
reduce PRV instability in short chilled liq-
uid loops, multi-pass chillers, parallel chiller
configurations and other applications that
cause PRV instability.
30% - Provides less sensitivity than the 50% selec-
tion. The longest allowed open or close pulse
is limited to 30% of the maximum allowed
with the NORMAL selection. This provides
less overall PRV movement than the 50%
selection. It’s beneficial in the same applica-
tions as the 50% selection, but that require
greater stability. This selection available with
Flash memory card version C.MLM.01.06.
xxx and later or C.MLM.04.02.xxx).
Flash memory card version C.MLM.01.06.xxx and
later or C.MLM.04.02.xxx have special variable speed
low load operation as follows: If the chiller is equipped
with the YORK Compressor Motor Variable Speed
Drive and the 50% or 30% Sensitivity is selected, the
Pre-rotation Vane (PRV) movement is reduced further
than described above when the chiller is operating at
low load. When the PRV position is less than 25% and
the Leaving Chilled Liquid Temperature is within plus
or minus 2.5 °F of setpoint, the maximum allowed
vane pulse is limited to 3.5 seconds at the 25% PRV
position and 0.9 seconds at 0% position. PRV positions
in between have linearly scaled maximums.
Proceed as follows to select this value:
1. At the keypad, log in at SERVICE access level
using access code 1 3 8 0.
2. Select EVAPORATOR Screen.
3. Press SENSITIVITY key.
4.
Use ◄ and ► keys to select desired value.
5. Press ENTER (
) key.
DROP LEG REFRIGERANT TEMPERATURE
The chiller can be equipped with a refrigerant tempera-
ture sensor in the drop leg between the condenser and
