York YCAL Series Installation Operation & Maintenance page 108

SECTION 7 - UNIT CONTROLS
S Y S X S P
D P
These displays show suction and discharge pressures
for each system. The discharge pressure transducer is
optional on some models.
If the optional discharge transducer is not installed, the
discharge pressure would display 0 psig (0 barg).
Some models come factory wired with a low pressure
switch in place of the suction transducer. In this case,
the suction pressure would only be displayed as the
maximum suction pressure reading of more than 200
psig (13.79 barg) when closed, or less than 0 psig (0
barg) when open.
The minimum limits for the display are:
Suction Pressure: 0 psig (0 barg)
Discharge Pressure: 0 psig (0 barg)
The maximum limits for the display are:
Suction Pressure: 200 psig (13.79 barg)
Discharge Pressure: 400 psig (27.58 barg)
S Y S X S U C T
S A T S U C T
S Y S X E E V
S U C T S H E A T
These messages will be displayed for each system, if
an EEV is installed in the system. The EEV % is the
EEV controller output.
S Y S X C O O L E R
R E F R I G T E M P = X X X . X ° F
Cooler inlet temperatures, as measured by the refriger-
ant temperature sensor in the cooler, will be displayed
on R-407c units for both systems.
S Y S X H O U R S
2 = X X X X X,
S Y S X S T A R T S
2 = X X X X X,
108
= 7 2 . 1 P S I G
= 2 2 7 . 0 P S I G
= X X X . X ° F
= X X X . X ° F
= X X X . X %
= X X X . X ° F
I N L E T
1 = X X X X X
3 = X X X X X
1 = X X X X X
3 = X X X X X
The above two messages will appear sequentially for
each system. The first display shows accumulated run-
ning hours of each compressor for the specific system.
The second message shows the number of starts for
each compressor on each system.
Run times and starts will only be dis-
played for the actual number of sys-
tems and compressors on the unit.
A total of 99,999 hours and starts can be logged before
the counter rolls over to "0".
L O A D T I M E R
U N L O A D T I M E R
This display of the load and unload timers indicate
the time in seconds until the unit can load or unload.
Whether the systems loads or unloads is determined by
how far the actual liquid temperature is from setpoint.
A detailed description of unit loading and unloading is
covered under the topic of Capacity Control.
C O O L I N G
2 O F
The display of COOLING DEMAND indicates the
current "step" in the capacity control scheme when in
Return Water Control Mode. The number of available
steps are determined by how many compressors are in
the unit. In the above display, the "2" does not mean
that two compressor are running but only indicates that
the capacity control scheme is on step 2 of 8. Capacity
Control is covered in more detail in this publication
which provides specific information on compressor
staging (for Return Water Control only).
T E M P E R R O R
T E M P R A T E
The COOLING DEMAND message will be replaced
with this message when Leaving Chilled liquid control
is selected. This message indicates the temperature er-
ror and the rate of change of the chilled liquid tempera-
ture.
L E A D S Y S T E M
S Y S T E M
FORM 150.66-NM3
ISSUE DATE: 09/25/2020
5 8 S E C
0 S E C
D E M A N D
8 S T E P S
X X X . X ° F
X X X . X ° F / M
I S
N U M B E R 2
JOHNSON CONTROLS