Specifications

50
JOHNSON CONTROLS
Form 201.28-NM1.EN.PED/CE (0211)
OPERATION
The ◄ (LEFT ARROW) key allows programming the
default value when programming numeric values. For
changing numeric values, the ► (RIGHT ARROW) key
has no function.
The ◄ ► (ARROW) keys also allow scrolling sideways
between the same displays on different systems. For
example, pressing the ► (RIGHT ARROW) key while
viewing the system #1 suction pressure moves the
display to system #2 suction pressure.
Pressing the ◄ (LEFT ARROW) key moves the
opposite direction. The arrow keys also allow fast
scrolling through data under keys such as HISTORY by
enabling the operator to move between subgroups of data
such as Unit, System, and VSD data.
Keypad Data Entry Mode
For numeric programmable items, the data entry mode is
entered by pressing any of the number keys, the decimal
point key, or the +/- key. When the data entry mode is
entered, the data from the key press will be entered and
the cursor will appear under the position where the data
is being entered.
For non-numeric programmable items, data entry mode
is entered by pressing the ◄ or ► (ARROW) keys.
When the data entry mode is entered, the cursor will
appear under the first position of the non-numeric string.
The programmable choice may be changed by pressing
the ◄ or ► (ARROW) keys.
To exit the data entry mode and store the programmed
value, the(ENTER) key must be pressed. When the
 (ENTER) key is pressed, the cursor will disappear.
The data entry mode may also be exited by pressing
the X (CANCEL) key. The programmed data will be
returned to its original value when the X (CANCEL) key
is pressed.
When the data entry mode is exited, the cursor will
disappear. If any other key is pressed while in the
Data Entry Mode, the following display will appear
for 2 seconds indicating the user must choose between
accepting or canceling the change:
PRESS  TO ACCEPT VALUE OR
X TO CANCEL DATA ENTRY
If the  (ENTER) key was pressed from the data
entry mode and the numeric value entered was out of
range, the following message will appear for 2 seconds
followed by the original data display.
OUT OF RANGE - TRY AGAIN!
Display
The 80 character (2 lines of 40 characters per line)
display is a Liquid Crystal Display (LCD) used for
displaying unit parameters, system parameters, and
operator messages. The display has an LED backlight
background for night viewing and is viewable in direct
sunlight.
Anti-recycle Timer
On power-up of the control panel, the anti-recycle timer
for each system will be set to 120 seconds and must time
out before a compressor is allowed to start.
Whenever a system starts, the anti-recycle timer for all
systems will be set to 120 seconds and will count down
from the time the motor starts. The timer must time out
before another compressor is allowed to start.
Whenever a system shuts down, the anti-recycle timer
for that system will be set to 120 seconds. The timer
must time out before the system is allowed to restart.
Evaporator Pump Control
The evaporator pump dry contacts are energized when
any of the following conditions are true:
• If a Low Leaving Chilled Liquid Fault occurs.
• Whenever a compressor is running.
• The Daily Schedule is ON and the UNIT switch is
ON.
Even if one of above is true, the pump will not run if the
panel has been powered up for less than 30 seconds or if
the pump has run in the last 30 seconds to prevent pump
motor overheating.
Evaporator Heater Control
The evaporator heater is controlled by ambient air
temperature. If no systems are running and the
ambient temperature drops below 4.4 °C (40°F), the
heater is turned ON. If no systems are running and the
temperature rises above 7.2°C (45°F) the heater is turned
OFF. Whenever a system is running, the evaporator
heater is turned OFF. Both evaporator heater outputs
will always be turned ON and OFF together. An under
voltage condition will keep the heater OFF until full
voltage is restored to the system. The heater will protect
the evaporator from freeze-up down to -29°C(-20°F ).