30
YORK INTERNATIONAL
MON XX:XX AM AUX SAFETY SHUTDOWN
The system is shut down because an external device,
connected to digital input board TB1-31 (Auxiliary
Safety Shutdown Input), has initiated a system shut-
down. This input is a general purpose input that can be
used to annunciate a user-defined safety shutdown.
To restart chiller, press
COMPRESSOR
switch to
STOP-RESET
position and then to
START
position.
REPLACE RTC. U16 REPROGRAM SETPOINTS
Indicates that the battery located inside the
REAL-TIME
CLOCK
IC chip (U16 on the Micro Board) is defective.
This battery provides back-up power to the RTC
memory (RAM) in the event of a utility AC power fail-
ure. This assures the system setpoints will be main-
tained. If this message appears, the RTC IC chip (U16)
on the Micro Board must be replaced. If there had been
a power failure while this message is displayed, the
setpoints will have been lost and must be repro-
grammed. Order a replacement RTC IC chip (YORK
part number 031-00955-000) from the YORK Parts Dis-
tribution Center. With AC power removed from system,
locate RTC chip
U16
on the Micro Board and remove
existing RTC chip from socket and discard. Observe
anti-static precautions and install new RTC chip in
socket. Assure proper IC orientation orientation notch
must be
UP
. (Refer to Fig. 14.)
MON XX:XX AM OPEN DRAIN TEMP THERMOCOUPLE
The chiller is shut down because the Proximity/Tem-
perature Sensor thermocouple or high speed drain
temperature wiring between the Proximity/Tempera-
ture Sensor module and the MicroComputer Control
Center has been disconnected or has a poor electrical
connection.
IMPORTANT:
Open thermocouple shutdowns would
typically indicate hardware or wiring defects and should
not result in any damage to the compressor high speed
thrust bearing. Therefore, a bearing inspection is not
required. However, due to the critical nature of these
circuits, anytime this shutdown occurs, a special reset
procedure must be performed by a qualified service
technician before the chiller can be restarted. This pro-
cedure is detailed in Service manual, Form 160.49-M2.
MON XX:XX AM DC UNDERVOLTAGE
The Proximity/Temperature Sensor module becomes
unstable in operation when the +24VDC supply de-
creases to +17VDC. Therefore, the Micro Board moni-
tors the +24VDC supply and when it decreases to
+19VDC, it shuts down the chiller and displays this
message, preventing invalid Proximity Sensor Safety
or High Speed Drain Temp safety shutdowns. The
chiller will automatically restart when the voltage in-
creases to greater than +19.7 VDC.
FIG. 14
MICROCOMPUTER CONTROL CENTER
LOCATION OF REAL TIME CLOCK U16
RTC IC CHIP
24673A
MICRO BOARD
U16 RTC
IC CHIP
REAL
TIME
CLOCK