York MILLENNIUM YCAS, Installation Operation & Maintenance

Page: 134 / 152

134 YORK INTERNATIONAL
7.4 MANUAL OVERRIDE KEY
When the Manual Override key is pressed, the Daily
Schedule programmed into the chiller is ignored and the
chiller will start up when water temperature is above
the high limit of the Control Range, the Chiller ON/OFF
switch is ON, remote cycling devices are CLOSED,
and system switches permit.
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 is only
active for a period of 30 minutes and the following sta-
tus message will be observed:
M A N U A L
O V E R R I D E
If a “Warning - Low Battery” fault
message appears on the display the in-
ternal clock, calendar and program
settings cannot be relied on for accu-
racy. Default values are loaded into the
microprocessor memory and the
Manual Override key can be used to
zero out the daily schedule and allow
unlimited operation regardless of the
time on the internal clock. Repro-
gramming of the setpoints and cutout
values may also be necessary. When the
MANUAL OVERRIDE key is pressed
the low battery message will disappear.
If a power failure should again occur,
the above process will again need to
be repeated to bring the chiller back
on line. See also Section 2.5.
Micropanel