York Millennium YCAJ150, Installation Operation & Maintenance, Page: 38 / 116

38 YORK INTERNATIONAL
SWITCH 8
OPEN:
Fan control will be by outside ambient temp. This will be
the standard mode of fan control for normal operation. In
this mode, maximum chiller efficiency will be achieved. If
the Low Ambient option is installed, the fan control will
automatically change to pressure control at temperatures
below 25°F (-3.9°C). See page 79 for fan control sequence.
CLOSED:
Fan control is by discharge pressure only. This mode of
fan control will increase discharge pressure. It should be
used if nuisance low suction pressure faults are experi-
enced. See page 93 for fan control sequence.
NOTE: Discharge pressure transducers must be in-
stalled. These are optional (Discharge Pressure
Read-out Option) unless a Low Ambient Kit is
installed.
SWITCH 7
OPEN:
SYS 1 can be selected as the lag compressor by clos-
ing a user supplied contact between Terminals 13 and
19. See Page 74.
CLOSED:
In this mode, the micro determines which compressor is
assigned to the lead and the lag. A new lead/lag assign-
ment is made whenever both compressors shut down.
The micro will then assign the “lead” to the compressor
with the shortest anti-recycle time.
M A N U A L
L E A D / L A G
A M B I E N T & D I S C H P R
F A N C O N T R O L
A U T O M A T I C
L E A D / L A G
D I S C H A R G E P R E S S U R E
F A N C O N T R O L