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YORK INTERNATIONAL
FORM 150.63-NM1
99
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
affected system will occur when the discharge pressure
drops to 85% of the unload pressure and 10 minutes
have elapsed.
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.
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 sec-
onds and after the suction pressure rises above the suc-
tion pressure limit point.
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 or an ISN
controller could be sending a load limit command.
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
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
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
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
S Y S 1 Z O N E T H E R M O F F
S Y S 2 Z O N E T H E R M O F F
3
The COMPS RUNNING message indicates that the re-
spective system is running due to demand. The “X” will
be replaced with the number of compressors in that sys-
tem that are running.
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.
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 pro-
grammed for Suction Pressure control.
The anti-coincident 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-coincident timer is only present on
two system units.
When this message appears, discharge pressure limit-
ing is in effect. The Discharge Pressure Limiting fea-
ture is integral to the standard software control; how-
ever the discharge transducer is optional. Therefore, it
is important to keep in mind that this control will not
function unless the optional discharge transducer is in-
stalled in the system.
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
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 %
Summary of Contents for MILLENNIUM YCUL0016SC
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