Unit Warning; Microboard (331-03478-Xxx) - York YVAA Installation Operation & Maintenance

SECTION 7 - OPERATION
• The Flow Switch is closed.
• Leaving Chilled Liquid Setpoint is above the
Setpoint plus CR (Setpoint High Limit).
Once the precharge takes place, if the anti-recycle tim-
er is timed out the chiller control system on the Chiller
Control Board will select the number of compres-
sors to start and begin operation of the compressors.
The compressors speed is ramped to the minimum start
frequency and increase speed as needed in an effort to
regulate the leaving chilled liquid temperature to meet
the required Setpoint.

Unit warning

Unit warning operation
Unit warnings are caused when a condition is
present requiring operator intervention to restart the
unit. All setpoints, program values, and options should
be checked before operating the unit. Warnings are not
logged to the history buffer. If a unit warning is in ef-
fect, the message is displayed to the operator when the
STATUS key is pressed.
Low battery warning
The LOW BATTERY WARNING can only occur at
unit power-up. On micropanel power-up, the RTC
battery is checked to see if it is still operational. If
it is, normal unit operation is allowed. If the battery
voltage is determined to be low, the following warning
message is displayed indefinitely.
UNIT WARNING: !! LOW BATTERY !!
CHECK SETPOINTS/PROGRAM/OPTIONS/TIME
If a low battery condition exists, all programmed
setpoints, program values, time, schedule, and history
buffers will have been lost. These values will all be
reset to their default values, which may not be the
preferred operating values. Once a bad battery is
detected, the unit will be prevented from running un-
til the MANUAL OVERRIDE key is pressed. Once
the MANUAL OVERRIDE key is pressed, the anti
recycle timers will be set to the programmed default anti
recycle time to allow the operator sufficient time to
check setpoints, program values, and so on.
If a low battery is detected, it should be replaced as
soon as possible. The programmed values will all be
lost and the unit is prevented from running on the next
power interruption.
102

Microboard (331-03478-XXX)

The 331-03478-xxx microboard utilizes the IPU3 pro-
cessor. The IPU3 processor supports BAS Communi-
cation through the use of the SC-EQ Communications
Card. The IPU3 processor and 03478 board in addition
to the SD also has USB which can be used for software
downloads and data logging.
See
Figure 49 on page 104 to locate the following
ports of the 03478 microboard.
Power supplies and LEDs
The 03478 has LEDs to indicate various states of op-
eration of the microboard.
STATUS – Flashes every 1/2 second to indicate that
the base board processor is running its program.
POWER – On solid indicates that the base board +12
V and +5 V power supplies are operational.
TX1 – Red LED flashes when transmitting data out
Port 1 TB3 (SC-EQ port).
RX1 – Green LED flashes when receiving data in Port
1 TB3.
TX2 – Red LED that flashes when transmitting data
out Port 2 (TB2 or printer TB1).
RX2 – Green LED that flashes when receiving data in
Port 2 (Datalogging TB2 or printer TB1).
VSD_TX – Red LED that flashes when transmitting
data out Port 3 to the VSD Logic board.
VSD_RX – Green LED that flashes when receiving
data in Port 3 from the VSD Logic board.
Form 201.47-ICOM1
Issue date: 17/11/2022
JOHNSON CONTROLS