Table of Contents
Advertisement
On power-up the microprocessor will check the Real Time
Clock (RTC Chip) battery to assure that the internal
battery is still operational. This is accomplished by
performing an RTC RAM location check. As long as the
battery checks out, the micro will continue on with
business without interruption.
If a check is made and the battery has failed, the
microprocessor will not allow the chiller to run and the
following STATUS message will appear:
! ! W A R N I N G ! !
! ! L O W
B A T T E R Y ! !
Under low battery conditions, the only way to run the
chiller is to press the "MANUAL OVERRIDE" key. The
"MANUAL OVERRIDE" key will function differently than
it does in service situations where it overrides the daily
schedule for only 30 minutes. In a low battery condition,
the "MANUAL OVERRIDE" key will zero out the daily
schedule to allow unlimited operation regardless of the
time on the internal clock. Default values will also be
loaded into memory for all setpoints and cut-outs. These
may require reprogramming to assure they meet the
chiller operating requirements for operation board 30
minutes. In addition, the low battery message which is
displayed for this condition will disappear.
NOTE: If a power failure should again occur, the above
process will again need to be repeated to bring
the chiller back on line.
In the unlikely event the low battery message should ever
appear, it will require the RTC Chip U13 on the
Microprocessor Board (Fig. 39) to be replaced. Care
should be taken to assure that the chip is properly
installed. Pin 1 (dimple in the top of the chip) must be
oriented as shown in Fig. 39. The part number of the RTC
Chip is 031-00955-000.
COMPRESSOR HEATER
The Compressor Heater in each compressor will be ON
for the first five minutes after the compressor is shut
down. Then the heater is controlled by discharge
temperature. If the heater is ON and the discharge
temperature rises above 170°F will shut off. If the heater
is OFF and the discharge temperature falls below 100°F,
it will turn ON. The heater is controlled by the
microprocessor.
The purpose of the heater is to prevent the migration of
refrigerant into the compressor during shutdown, assuring
proper lubrication of the compressor on start-up.
Anytime power is removed from the chiller for more than
an hour, 115VAC control power should be reapplied to
allow the compressor heaters to remain on for 24 hours
prior to restart.
128
CLOCK JUMPER
FIG. 39 – CLOCK JUMPER
EVAPORATOR HEATER
The evaporator heater prevents water standing in the
evaporator from, freezing. Whenever the outdoor ambient
temperature drops below 40°F, the microprocessor will
turn the evaporator heaters ON. If temperature rises
above 45°F, the heater will be turned off.
METRIC DISPLAY
The control panel is capable of providing displays of
pressures
and
temperatures
Temperatures will be displayed in °C and pressures in
Bars.
A Metric to English temperature conversion table is
provided on the back cover of this
be converted from PSIG to Bars using the formula 1 Bar
= 14.504 PSIG.
To obtain displays in Metric, Switch 5 Dip switch S1 on the
Microprocessor Board must be placed in the closed (on)
position (Page 80). The positioning of this switch can be
verified by pushing the OPTIONS key and verifying that
"SI UNITS READOUT" is programmed (Page 79).
PIN 1
RTC
26001A
in
metric
values.
manual.
Pressure can
YORK INTERNATIONAL
Advertisement
Table of Contents
