JOHNSON CONTROLS
79
FORM 150.62-NM6 (103)
The above two messages will appear sequentially for
each system. The rst display shows accumulated run-
ning hours of each compressor for the specic system.
The second message shows the number of starts for
each compressor on each system.
S Y S X S P = 7 2 . 1 P S I G
D P = 2 2 7 . 0 P S I G
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 >200 PSIG (13.79
barg) when closed, or < 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)
These messages will be displayed for each system, if an
EEV is installed in the system. The EEV % is the EEV
controller output.
Cooler inlet temperatures, as measured by the refrig-
erant temperature sensor in the cooler, will be displayed
on R-407c units for both systems.
Run times and starts will only be dis-
played for the actual number of sys-
tems and compressors on the unit.
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.
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 com-
pressor 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
specic information on compressor staging (for Return
Water Control only).
The COOLING DEMAND message will be replaced
with this message when Leaving Chilled liquid control
is selected. This message indicates the temperature
error and the rate of change of the chilled liquid tem-
perature.
2
S Y S X S U C T = X X X . X ° F
S A T S U C T = X X X . X ° F
S Y S X E E V = X X X . X %
S U C T S H E A T = X X X . X ° F
S Y S X H O U R S 1 = X X X X X
2 = X X X X X, 3 = X X X X X
C O O L I N G D E M A N D
2 O F 8 S T E P S
L O A D T I M E R 5 8 S E C
U N L O A D T I M E R 0 S E C
S Y S X S T A R T S 1 = X X X X X
2 = X X X X X, 3 = X X X X X
S Y S X C O O L E R I N L E T
R E F R I G T E M P = X X X . X ° F
T E M P E R R O R X X X . X ° F
T E M P R A T E X X X . X ° F / M
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