36
YORK INTERNATIONAL
The micro will accept a range of programmable values
between 200-399 PSIG for this cut-out. For this cut-out
to be functional, the Discharge Pressure Readout Op-
tion must be installed.
NOTE: It is required to first key in “0” when program-
ming this cut-out (Example: 0275 PSIG).
More details on this safety are outlined in the SYSTEM
SAFETIES section.
OUTSIDE AIR TMP LOW CUT-OUT
The OUTSIDE AIR TMP LOW CUT-OUT allows the user
to select the chiller low ambient temperature cutout point.
If the ambient falls below this point the chiller will shut
down. Restart can occur, if demand allows, when tem-
perature rises above the cut-out. This only applies to
outdoor air-cooled chillers.
For normal ambient applications, the cut-out is set at
25.0°F and is NOT programmable. However, some users
may set the cut-out higher to shut down the chiller and
take advantage of other less costly cooling sources. In
this case, S1 Dip Switch #2 on the Micro Logic Board
must be in the CLOSED position for Low Ambient Con-
trol to allow programming the cut-out above 25°F.
Low ambient applications in ambients less than 25.0°F
require a low ambient kit to be installed. Otherwise nui-
sance low pressure and low motor current trips will re-
sult. If a low ambient kit is installed, the cut-out may be
lowered as needed below 25°F. If operation is occa-
sionally needed below 0°F. the cut-out should be set at
00.0°F. This will allow operation at any temperatures since
the micro is only able to recognize temperatures above
1°F, regardless of the display.
NOTE: Operation below 0°F may cause other types of
nuisance safety shutdowns, but occasional shut-
downs can usually be tolerated since the need
for sustained operation at these temperatures
is unlikely and temperatures rarely stabilize for
any length of time below 0°F.
To program the OUTSIDE AIR TMP LOW CUT-OUT, key
in the desired value and press the ENTER key. The new
value will be entered into memory and the display will
advance to the next user programmable limit.
The micro will accept a range of programmable values
between 00.0° - 50.0°F for this cut-out, if S1 Dip Switch
#2 on the Micro Logic Board is in the CLOSED position.
In the OPEN position, afixed 25°F cut-out is recognized.
OUTSIDE AIR TMP HIGH CUT-OUT
The OUTSIDE AIR TMP HIGH CUT-OUT is selectable to
establish the high ambient cut-out point. If the ambient
rises above this point, the chiller will shut down. Restart
can occur when temperature drops below the cut-out.
This only applies to outdoor air-cooled chillers.
This cut-out is normally set at 130.0°F to allow opera-
tion to the absolute maximum temperature capability of
the electro-mechanical components.
To program the OUTSIDE AIR TMP HIGH CUT-OUT, key
in the desired value and press the ENTER key. The new
value will be entered into memory and the display will
advance to the next user programmable limit.
The micro will accept a range of programmable values
between 100.0° - 130.0°F for this cut-out.
DISCHARGE PRESSURE UNLOAD
The DISCHARGE PRESSURE UNLOAD point is a pro-
grammable limit to keep the system from faulting on the
high discharge pressure cut-out should a system prob-
lem or chiller problem occur. A typical problem would be
if the cooling tower would become dirty on a water-cooled
system. Pressure would rise and eventually cause the
chiller to fault causing total loss of cooling. By unloading
the compressors at high discharge pressures, the chiller
is allowed to continue to run automatically at reduced
capacity until the dirty cooling tower can be attended to.
When the unload point is reached, the micro will auto-
matically totally unload the affected compressor. Typi-
cal maximum programmed limits would be 375 PSIG for
air-cooled chillers with 395 or 405 PSIG high pressure
cut-outs and 255 PSIG for water-cooled chillers with 275
PSIG cut-outs.
Reloading will occur when the discharge pressure drops
to 60 PSIG below the programmed unload pressure and
will increment one stage at a time as dictated by the
loading timers.
To program the DISCHARGE PRESSURE UNLOAD, key
in the desired value and press the ENTER key. The new
value will be entered into memory and the display will
advance to the next user programmable limit.
O U T S I D E
A I R
T M P
L O W
C U T O U T
=
2 5 . 0
F
O U T S I D E
A I R
T M P
H I G H
C U T O U T
=
3 0 . 0
F
D I S C H A R G E
P R E S S U R E
U N L O A D
=
3 6 0
P S I G