York YLAA0195HE, Manual, Page: 162 / 206

JOHNSON CONTROLS
162
FORM 150.72-NM3 (1020)
ISSUE DATE 10/05/2020
SECTION 7 – UNIT CONTROLS
Option 4 – Ambient Control Type:
The low ambient cutout is adjustable from 25 °F to 60 °F
(-3.9 °C to 15.6 °C).
or
The low ambient cutout is programmable down to 0 °F
(-17.8 °C). A low ambient kit MUST be installed for
this option to be chosen. If the kit is NOT installed,
and low ambient is selected, low pressure faults and
compressor damage may occur.
Option 5 – Local/Remote Control Type:
When programmed for LOCAL, an ISN or RCC control
can be used to monitor only. The micropanel will operate
on locally programmed values and ignore all commands
from remote devices, or through the RS-485 inputs. The
chiller will communicate and send data to the remote
monitoring devices.
or
This mode should be selected when an ISN or RCC
control is to be used to control the chiller. This mode
will allow the ISN to control the following 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 6 – Unit Control Mode:
Unit control is based on return chilled liquid temperature.
Return Chilled Liquid Control can only be selected on
units that have 4 to 6 compressors (dual system units).
L O C A L / R E M O T E M O D E
R E M O T E
A M B I E N T C O N T R O L
L O
W A M B I E N T
L O C A L / R E M O T E M O D E L
L O C A L
C O N T R O L M O D E
R E T U R N L I Q U I D
A M B I E N T C O N T R O L
S T A N D A R D
C O N T R O L M O D E
L E A V I N G L I Q U I D
Unit control is based on leaving chilled liquid temp.
Leaving Chilled Liquid Control can only be selected on
units that have 4 to 6 compressors (dual system units).
Option 7 – 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 Imperial
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 Scientific
International Units of °C or barg.
Option 8 – 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 chillers
with 2 refrigerant systems. Auto lead/lag allows
automatic 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 microprocessor board will
then assign the “lead” to the system with the shortest
average run time.