JOHNSON CONTROLS
125
SECTION 7 – UNIT CONTROLS
FORM 150.73-NM1
ISSUE DATE: 09/04/2020
7
The software may skip the low ambient
selection, but a low ambient kit is still
needed to operate below 25°F.
Option 4 – Local/Remote Control Type
L O C A L / R E M O T E M O D E L
L O C A L
When programmed for LOCAL, an ISN or RCC con-
trol can be used to monitor only. The micro panel will
operate on locally programmed values and ignore all
commands from the remote devices. The condensing
unit will communicate and send data to the remote
monitoring devices.
or
L O C A L / R E M O T E M O D E
R E M O T E
This mode should be selected when an ISN or RCC
control is to be used to control the condensing unit.
This mode will allow the ISN to control the follow-
ing items: Remote Start/Stop, Cooling Setpoint, Load
Limit, and History Buffer Request. If the unit receives
no valid ISN transmission for 5 minutes, it will revert
back to the locally programmed values.
Option 5 – Unit Control Mode
C O N T R O L M O D E
S U C T I O N P R E S S U R E
Unit control is based on Suction Pressure Control.
or
C O N T R O L M O D E
D I S C H A R G E A I R
Unit control is based on Discharge Air Temp. Control.
Option 6 – Display Units
D I S P L A Y U N I T S
I M P E R I A L
This mode displays system operating values in Impe-
rial units of °F or psig.
or
D I S P L A Y U N I T S
S I
This mode displays system operating values in Scien-
tific International Units of °C or barg.
Option 7 – Lead/Lag Type (two system units
only)
L E A D / L A G C O N T R O L
M A N U A L S Y S 1 L E A D
SYS 1 selected as lead compressor. SYS 1 lead option
MUST be chosen if Hot Gas Bypass is installed.
or
L E A D / L A G C O N T R O L
M A N U A L S Y S 2 L E A D
SYS 2 selected as lead compressor.
or
L E A D / L A G C O N T R O L
A U T O M A T I C
Lead/lag between systems may be selected to help
equalize average run hours between systems on con-
densing units with 2 refrigerant systems operating on
discharge air temp control. Auto lead/lag allows auto-
matic lead/lag of the two systems based on an average
run hours of the compressors in each system. A new
lead/lag assignment is made whenever all compressors
shut down. The micro will then assign the “lead” to the
system with the shortest average run time.
Option 8 – Condenser Fan Control Mode
F A N C O N T R O L
D I S C H A R G E P R E S S U R E
Condenser fans are controlled by discharge pressure
only. This mode may only be chosen when discharge
pressure transducers are installed.
F A N C O N T R O L
A M B I E N T & D S C H P R E S S
Condenser fans are controlled by ambient temperature
and discharge pressure. This mode must be chosen if
the discharge pressure transducers are not installed.
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