York YLUA0248 Series Installation Operation & Maintenance page 98

SECTION 7 – UNIT CONTROLS
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 micro
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.
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 micro will automati-
cally unload the affected system by de energizing one
compressor. The discharge pressure unload will occur
when the discharge pressure gets within 15 PSIG of the
programmed discharge pressure 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 occur 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 limit-
ing is in effect. The suction pressure limit is a control
point that limits the loading of a system when the suc-
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tion pressure drops to within 15% above the suction
pressure cutout. On a standard system programmed
for 80 PSIG/5.52 Bar suction pressure cutout, the mi-
cro would inhibit loading of the affected system with
the suction pressure less than or equal to 1.15 * 80
PSIG/5.52 Bar = 92 PSIG/6.34 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
unit will start-up when chilled liquid temperature al-
lows, 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
OVERRIDE is to only be used in emergencies or for
servicing. Manual override mode automatically disables
itself after 30 minutes.
S Y S 1 P U M P I N G
S Y S 2 P U M P I N G
The PUMPING DOWN message indicates that a com-
pressor in the respective system is presently in the pro-
cess of pumping the system down. When pumpdown is
initiated on shutdown, the liquid line solenoid or EEV
will close and a compressor will continue to run. When
the suction pressure decreases to the suction pressure
cutout setpoint or runs for 180 seconds, whichever
comes first, the compressor will cycle off.
FAULT SAFETY STATUS MESSAGES
Safety Status messages appear when safety thresholds
in the unit have been exceeded. Safeties are divided
into two categories – system safeties and unit safeties.
System safeties are faults that cause the individual sys-
FORM 150.73-NM2
ISSUE DATE: 09/07/2020
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JOHNSON CONTROLS