York MILLENNIUM YCAS 250 Manual Download

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YORK INTERNATIONAL

lower temperatures. If operation is occasionally needed
below 1°F (-17°C), the cutout should be set at 00.0°F.
This will allow operation at any temperature, as the mi-
cro will only recognize temperatures above 1°F (-17°C).
Temperatures below 1°F (-17°C) 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 1°F (-17°C) 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 1°F (-17°C) for more than
a short time.

Low Leaving Liquid Temperature Cut-Out

The Low Leaving Liquid Temperature Cutout protects
the evaporator from damage due to ice build up caused
by operation below the chilled liquid freezing point.

If the leaving chilled liquid temperature (water or gly-
col) drops below the cutout point, the chiller will shut
down. The chiller will restart automatically when tem-
perature rises more than 4°F (2°C) above the cutout
point and cooling demand exists.

If the Dip Switch on the microprocessor board is set for
“Water Cooling” (see Section 3.7, page 158) the cutout
is automatically set at 36°F (2°C) and cannot be repro-
grammed. If the Switch is set for “Brine Cooling” (gly-
col) the cutout can be programmed between 08.0 - 36.0°F
(-13 through -2°C). The cutout should normally be set to
4°F (2°C) below the setpoint minus the range, i.e. 34°F
(setpoint) – 2°F (range) - 4°F = 28°F (see Section 6, page
169).

To program the Leaving Liquid Temperature Cutout, key
in the required setting and press the Enter key to store
the value into memory and scroll to the next display.

High Motor Current Unload Point

The Motor Current Unload point is used to avoid a high
motor current safety shutdown by unloading a compres-
sor, if current draw approaches the maximum limit cut-

be set to the saturated refrigerant pressure equivalent
to 18°F (10°C) below the lowest temperature of the
programmed chilled liquid Control Range (Section 6).
This programmable value is password protected.

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 Cut-Out

The High Ambient Cutout is used to select the ambient
temperature above which the chiller may not operate.
If the ambient temperature rises 1°F (1°C) 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 130°F (54°C) to allow
operation to the absolute maximum temperature capa-
bility of the electromechanical components; however,
values between 100.0 - 130.0°F (38 - 54°C) 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.

Low Ambient Temperature Cut-Out

The Low Ambient Cutout is used to select the ambient
temperature below which the chiller may not operate.
If the ambient temperature falls 1°F (1°C) below this
point, the chiller will shut down. Restart will occur au-
tomatically, when temperature rises more than 1°F (1°C)
above the cutout and cooling demand is present (see
also Section 2.5 page 151). This programmable value
is password protected.

If the SW1 Dip Switch on the Microprocessor Board
is set for “Standard Ambient Control” (see Section
3.7) the low ambient cutout is set at 25°F (-4°C) and
is NOT programmable. If the Dip Switch is set for
“Low Ambient Control”, programming of the cutout
between 00.0 - 50.0°F (8 - 10°C) is allowed. This al-
lows higher values than 25° F (-4°C) to be programmed
to shut down the chiller when other cooling methods
become operational. Values below 25°F (-4°C) can be
used for applications requiring chiller operation at

H I G H

A M B I E N T

T E M P

C U T O U T

1 3 0 . 0 ° F

L O W

A M B I E N T

T E M P

C U T O U T

2 5 . 0 ° F

L E A V I N G

L I Q U I D