144
YORK INTERNATIONAL
FORM 150.52-NM2 (1001)
Low Ambient Temperature Cutout:
The Low Ambient Cutout is used to select the ambient
temperature below which the chiller may not operate.
If the ambient temperature falls 1°C (1°F) below this
point, the chiller will shut down. Restart will occur au-
tomatically, when temperature rises more than 1°C (1°F)
above the cutout and cooling demand is present (see
also Section 9 [2.5] page 118). This programmable value
is password protected.
If the SW1 Dip Switch on the Microprocessor Board
is set for "Standard Ambient Control" (see Section 9
[3.7]) the low ambient cutout is set at -4°C (25°F) and
is NOT programmable. If the Dip Switch is set for
“Low Ambient Control”, programming of the cutout
between -18 - 10°C (0.0 - 50.0°F) is allowed. This
allows values higher than -4°C (25° F) to be pro-
grammed to shut down the chiller when other cooling
methods become operational. Values below -4°C
(25°F) can be used for applications requiring chiller
operation at lower temperatures. If operation is occa-
sionally needed below -17°C (1°F), the cutout should
be set at -18°C (0.0°F). This will allow operation at
any temperature, as the micro will only recognize tem-
peratures above -17°C (1°F). Temperatures below -
17°C (1°F) will not be displayed.
To program the Low Ambient Cutout, key in the re-
quired setting and press the Enter key to store the value
into memory and scroll to the next display.
Operation below -17°C (1°F) may oc-
casionally cause nuisance low pres-
sure safety shutdowns. This will gen-
erally not cause a problem provided
ambient temperature is not expected
to be below -17°C (1°F) for more than
a short time.
This cutout value increases with time, until after 30 sec-
onds, it equals the programmed cutout value. If the suc-
tion pressure rises to above the programmed cutout value
during the 30-second time period, the timer will be reset.
If the suction pressure falls below the ramped cutout, the
system will shut down on a low pressure fault.
If the Dip Switch on the microprocessor board is set
for “Water Cooling” (see Section 9 [3.7]), the cutout is
programmable between 3-5 bar (44 - 70 PSIG) for both
R-22 and R-407C models. In this mode, settings of 3
bar (44 PSIG) for R-22 and R-407C are recommended.
If the Switch is set for “Brine Cooling” (glycol) the
cutout is programmable between 0.3 - 5 bar (5 - 70 PSIG)
for R-22 and R-407C models. In this mode, the cutout
should be set to the saturated refrigerant pressure
equivalent to 10°C (18°F) below the temperature of the
chilled liquid.
To program the Suction Pressure Cutout, key in the re-
quired setting and press the Enter key to store the value
into memory and scroll the next display.
High Ambient Temperature Cutout:
The High Ambient Cutout is used to select the ambient
temperature above which the chiller may not operate.
If the ambient temperature rises 1°C (1°F) above this
point, the chiller will shut down. Restart will occur au-
tomatically, when temperature falls more than 1°F (1°C)
below the cutout and cooling demand is present.
This cutout is normally set at 54°C (130°F) to allow
operation to the absolute maximum temperature capa-
bility of the electromechanical components; however,
values between 38 - 54°C (100.0 - 130.0°F) are accepted.
This programmable value is password protected.
To program the High Ambient Cutout, key in the re-
quired setting and press the Enter key to store the value
into memory and scroll to the next display.
H I G H
A M B I E N T
T E M P
C U T O U T
=
4 6 . 1 ° C
L O W
A M B I E N T
T E M P
C U T O U T
=
2 5 . 0 ° C
Micro Panel
