York MILLENNIUM YCUL0045SC Installation Operation & Maintenance page 99

S Y S 1 Z O N E
S Y S 2 Z O N E
These messages indicate that the zone thermostats for
system 1 and system 2 are open. These messages will
only be displayed when the Control Mode is programmed
for Suction Pressure control.
S Y S 1 A C
S Y S 2 A C
The anti-coincident timer is a software feature that guards
against 2 systems starting simultaneously. This assures
instantaneous starting current does not become exces-
sively high due to simultaneous starts. The micro limits
the time between compressor starts to 1 minute regard-
less of demand or the anti-recycle timer being timed out.
The anti-coincident 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 feature
is integral to the standard software control; however the
discharge transducer is optional. Therefore, it is impor-
tant to keep in mind that this control will not function
unless the optional 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 cut-
out due to high load or pull down conditions. When the
unload point is reached, the micro will automatically
unload the affected system by de-energizing one com-
pressor. The discharge pressure unload will occur when
the discharge pressure gets within 15 PSIG of the pro-
grammed discharge pressure cutout. This will only hap-
pen if the system is fully loaded, and will shut only one
compressor off. If the system is not fully loaded, dis-
charge limiting will not go into effect. Reloading the af-
fected 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 limiting
is in effect. Suction Pressure Limiting is only available
on units that have the suction pressure transducer in-
stalled. If a low pressure switch is installed instead, suc-
tion pressure limiting will not function.
YORK INTERNATIONAL
T H E R M O F F
T H E R M O F F
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
L I M I T I N G
L I M I T I N G
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 pressure cutout. On a
standard system programmed for 44 PSIG/3.0 Bar suc-
tion pressure cutout, the micro 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 suction pressure rises above the suction pres-
sure 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 limiting
could be due to the load limit/pwm input, or an ISN con-
troller could be 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 STATUS
DISPLAY will display this message. This will indicate
that the Daily Schedule is being ignored and the unit will
start up when demand is present, Remote Contacts, UNIT
switch and SYSTEM switches permitting. This is a pri-
ority message and cannot be overridden 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 MANUAL OVERRIDE mode.
MANUAL OVERRIDE is to only be used in emergen-
cies or for servicing. Manual override mode automati-
cally 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, the liquid line solenoid will close and a com-
pressor will continue to run. When the suction pressure
decreases to the suction pressure cutout setpoint, the
compressor will cycle off. If pump down cannot be
achieved three minutes after the liquid line solenoid
closes, the compressor will cycle off.
FAULT STATUS MESSAGES
Safeties are divided into two categories - system safe-
ties and unit safeties. System safeties are faults that
cause the individual system to be shut down. Unit safe-
ties are faults that cause all running compressors to be
shut down. Following are display messages and expla-
nations.
FORM 150.63-NM2
L I M I T X X %
L I M I T X X %
D O W N
D O W N
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