JOHNSON CONTROLS
102
FORM 150.27-NM1
ISSUE DATE: 09/30/2015
SECTION 7 – UNIT CONTROLS
S Y S 1 N O C O O L L O A D
S Y S 2 N O C O O L L O A D
This message informs the operator that the chilled liq-
uid temperature is below the point (determined by the
setpoint and control range) that the microprocessor
will bring on a system or that the microprocessor has
not loaded the lead system far enough into the loading
sequence to be ready to bring the lag system ON. The
lag system will display this message until the loading
sequence is ready for the lag system to start.
S Y S 1 C O M P S R U N X
S Y S 2 C O M P S R U N X
The COMPS RUNNING message indicates that the
respective system is running due to demand. The “X”
will be replaced with the number of compressors in
that system that are running.
S Y S 1 A R T I M E R X X S
S Y S 2 A R T I M E R X X S
The anti-recycle timer message shows the amount of
time left on the respective systems anti-recycle timer.
This message is displayed when the system is unable to
start due the anti-recycle timer being active.
S Y S 1 A C T I M E R X X S
S Y S 2 A C T I M E R X X S
The anti-coincidence timer is a software feature that
guards against 2 systems starting simultaneously. This
assures instantaneous starting current does not become
excessively high due to simultaneous starts. The mi-
croprocessor limits the time between compressor starts
to 1 minute regardless of demand or the anti-recycle
timer being timed out. The anti-coincidence timer is
only present on two system units.
S Y S 1 D S C H L I M I T I N G
S Y S 2 D S C H L I M I T I N G
When this message appears, Discharge Pressure Limit-
ing is in effect. The Discharge Pressure Limiting fea-
ture is integral to the standard software control; howev-
er the discharge transducer is optional on some models.
Therefore, it is important to keep in mind that this con-
trol will not function unless the discharge transducer is
installed in the system.
The limiting pressure is a factory set limit to keep the
system from faulting on the High Discharge Pressure
Cutout due to high load or pull down conditions. When
the unload point is reached, the microprocessor will
automatically unload the affected system by de ener-
gizing one compressor. The discharge pressure unload
will occur when the discharge pressure gets within 10
PSIG (0.69 barg) of the programmed discharge pres-
sure cutout. This will only happen if the system is fully
loaded and will shut only one compressor off. If the
system is not fully loaded, discharge limiting will not
go into effect. Reloading the affected system will oc-
cur when the discharge pressure drops to 85% of the
unload pressure and 10 minutes have elapsed.
S Y S 1 S U C T L I M I T I N G
S Y S 2 S U C T L I M I T I N G
When this message appears, suction pressure limiting is
in effect. The suction pressure limit is a control point
that limits the loading of a system when the suction pres-
sure drops to within 15% above the suction pressure cut-
out. On a standard system programmed for 44 PSIG (3.0
Bar) suction pressure cutout, the microprocessor would
inhibit loading of the affected system with the suction
pressure less than or equal to 1.15 x 44 PSIG (3.0 Bar)
equals 50 PSIG (3.5 Bar). The system will be allowed to
load after 60 seconds and after the suction pressure rises
above the suction pressure load limit point.
S Y S 1 L O A D L I M I T X X %
S Y S 2 L O A D L I M I T X X %
This message indicates that load limiting is in effect
and the percentage of the limiting in effect. This limit-
ing could be due to the load limit/pwm input, ISN or
RCC controller sending a load limit command.
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If MANUAL OVERRIDE mode is selected, the STA-
TUS display will display this message. This will indicate
that the Daily Schedule is being ignored and the chiller
will start-up when chilled liquid temperature allows, Re-
mote Contacts, UNIT switch and SYSTEM switches per-
mitting. This is a priority message and cannot be overrid-
den by anti-recycle messages, fault messages, etc. when
in the STATUS display mode. Therefore, do not expect to
see any other STATUS messages when in the MANUAL
OVERRIDE mode. MANUAL OVERRIDE is to only be
used in emergencies or for servicing. MANUAL OVER-
RIDE mode automatically disables itself after 30 minutes.
