York YLAA0041 Installation Operation & Maintenance page 164

Section 7: Unit controls
Option 7: Lead/lag type (two system units
only)
L E A D / L A G
M A N U A L
SYS 1 selected as lead compressor. SYS 1 lead option
MUST be chosen if Hot Gas Bypass is installed.
L E A D / L A G
M A N U A L
SYS 2 selected as lead compressor.
L E A D / L A G
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 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 microprocessor 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
Condenser fans are controlled by discharge pressure
only. This mode must be chosen.
F A N C O N T R O L
A M B I E N T &
Do not select this option on R-410A chillers.
164
C O N T R O L
S Y S 1 L E A D
or
C O N T R O L
S Y S 2 L E A D
or
C O N T R O L
P R E S S U R E
or
D S C H P R E S S
Option 9: Manual override mode
M A N U A L O V E R R I D E
D I S A B L E D
This option allows overriding of the daily schedule
that is programmed. MANUAL OVERRIDE MODE –
DISABLED indicates that override mode has no effect.
M A N U A L O V E R R I D E
E N A B L E D
Manual Override Mode is enabled. This is a service
function and when enabled, will allow the unit to start
when shut down on the daily schedule. It will auto-
matically be disabled after 30 minutes.
Form 150.72-ICOM6
Issue date: 12/19/2023
M O D E
or
M O D E
Johnson Controls