York YLAA Series Installation Operation & Maintenance page 110

SECTION 7 – UNIT CONTROLS
S Y S 1 N O
S Y S 2 N O
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
S Y S 2 C O M P S
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
S Y S 2 A R
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
S Y S 2 A C
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
S Y S 2 D S C H
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.
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C O O L L O A D
C O O L L O A D
R U N X
R U N X
T I M E R X X S
T I M E R X X S
T I M E R X X S
T I M E R X X S
L I M I T I N G
L I M I T I N G
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
S Y S 2 S U C T
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
pressure drops to within 15% above the suction pres-
sure cutout. On a standard system programmed for 44
PSIG/3.0 Bar suction pressure cutout, the micropro-
cessor would inhibit loading of the affected system
with the suction pressure less than or equal to 1.15 *
44 PSIG/3.0 Bar = 50 PSIG/3.5 Bar. The system will
be allowed to load after 60 seconds and after the suc-
tion pressure rises above the suction pressure load limit
point.
S Y S 1 L O A D
S Y S 2 L O A D
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.
M A N U A L
O V E R R I D E
If MANUAL OVERRIDE mode is selected, the STA-
TUS display will display this message. This will indi-
cate that the Daily Schedule is being ignored and the
chiller will start-up when chilled liquid temperature
allows, Remote Contacts, UNIT switch and SYSTEM
switches permitting. This is a priority message and can-
not be overridden by anti-recycle messages, fault mes-
sages, etc. when in the STATUS display mode. There-
fore, do not expect to see any other STATUS messages
when in the MANUAL OVERRIDE mode. MANUAL
FORM 150.72-ICOM6
ISSUE DATE: 12/29/2017
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JOHNSON CONTROLS