116
YORK INTERNATIONAL
FORM 150.52-NM2 (1001)
Normally, this key is only used for servicing when the
chiller is required to run, but the daily schedule is in an
OFF period. This key avoids the need to reprogram the
daily schedule. Once activated, Manual Override auto-
matically disables itself after 30 minutes.
Additional information regarding Manual Override is
outlined in Section 9, page 141.
2.3 UNIT WARNINGS
Unit Warnings are often caused by conditions which
require operator intervention to start the unit, or ex-
treme operating conditions. All setpoints and program-
mable values should be checked, if a chiller shutdown
occurred, before restarting the chiller. Unit Warnings
are not logged into the HISTORY BUFFER.
Low Battery Warning:
On power-up, the microprocessor will check the RTC
(Real Time Clock) memory back-up battery to make
sure it is still operational. Provided the battery checks
out, operation will continue normally. If a check is made
and the battery has failed, the microprocessor will not
allow the chiller to run and the above Status message
will appear.
If a low battery condition exists, the micro will restore
programmed cutouts, setpoints, and schedules to their
default values.
Once a low battery condition is
detected, the only way to run the
chiller is to use the Manual Override
key - see Section 9 (7.4). This allows
reprogramming of setpoints, cutouts,
and schedule.
The U13 RTC chip on the Microprocessor Board should
be replaced as soon as possible with YORK part # 031-
00955-000. Otherwise, the chiller will shutdown and
lose all programmed points, and require a MANUAL
OVERRIDE restart, if a power failure occurs.
Incorrect Refrigerant Warning:
The Incorrect Refrigerant Warning will occur if the DIP
Switch setting for refrigerant type and the type pro-
grammed into the micro “at the factory” are not the
same. This message will be displayed until the non-pro-
grammable “factory” programmed refrigerant type and
DIP Switch setting agree.
Power Failure Warning:
The Power Failure Warning will only be displayed on
“power restoration” after a “power loss”, if manual re-
start on power failure is selected under the PROGRAM
key (page 146). If manual restart on power failure has
been selected, the following warning message is dis-
played indefinitely on power restoration, and the chiller
will not run until the UNIT Switch is cycled OFF-and-
ON to restart the unit. This safety is available for users
who desire a chiller lock-out on power failure. NOTE:
This is typically not a desirable feature.
When this message appears, the chiller will not run and
the Unit Switch must be cycled OFF and ON to start
the unit. This display will only appear if “Manual Re-
start On Power Failure” is programmed under the Pro-
gram Key.
2.4 LIMIT / ANTICIPATION CONTROL
STATUS MESSAGES
Limit / anticipation controls are built into the software
to prevent safety shutdowns by automatically overrid-
ing the temperature controls, if system conditions ap-
proach safety thresholds. This avoids total loss of cool-
ing resulting from a lockout by a safety control.
Anticipation controls monitor discharge pressure, motor
current and suction temperature for each compressor
and, if programmed limits are exceeded, the affected
compressor’s load stage will be reduced one step, even
if requested to load by the leaving chilled liquid tem-
perature control routine. The micro will display a “Lim-
!! LOW BATTERY !!
CHECK PROG/ SETP / T IME
REPROGRAM TYPE OF
REFR I GERANT TO RUN
!! POWER FAILURE !!
CYCLE UNI T SWI TCH
Micro Panel
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