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FORM 150.75-NM2
45
YORK INTERNATIONAL
GENERAL
Pushing the PROGRAM key allows the user to program
“10” system operating limits. These limits include cut-
out points for safeties, anti-recycle timer duration, and
the reaction time of the microprocessor to abrupt
changes in the chilled water temperatures.
After the PROGRAM key is pressed, the micro will first
respond by displaying the DISCHARGE CUT-OUT. As
the “10” limits are displayed, they may be reprogrammed
using the “12” ENTRY keys. New values will be pro-
grammed into memory when the ENTER key is pushed.
The ENTER key must also be used to advance the dis-
play as the operator views the “10” system operating
limits. Each time the key is pushed, the display will ad-
vance to the next limit.
If the operator attempts to enter an unacceptable value,
the micro will respond with a momentary message indi-
cating the value selected has been ignored. This error
message is shown:
The “10” programmable limit displays are shown and
described below along with the range of values which
the microprocessor will accept for each limit.
THESE VALUES MUST BE CHECKED AND PROP-
ERLY PROGRAMMED WHEN COMMISSIONING THE
CHILLER. FAILURE TO PROPERLY PROGRAM
THESE VALUES MAY CAUSE DAMAGE TO THE
CHILLER OR OPERATION PROBLEMS.
DISCHARGE CUT-OUT
The DISCHARGE CUT-OUT is a microprocessor back-
up for the mechanical high pressure cut-out located in
each refrigerant circuit. Typically, chillers with air-cooled
condensers should have the cut-out set at 395 PSIG.
Chillers with water-cooled condensers normally require
the cut-out to be set at 275 PSIG.
NOTE: In some water cooled condenser installations,
the possibility exists for the condenser water
pump or the cooling tower to not be in opera-
tion when the chiller starts. This causes the dis-
charge pressure to rise so rapidly that even
though the mechanical high pressure cut-out is
shutting down the compressor, the flywheel ef-
fect may cause the pressure to continue to rise
causing the relief valve to open with a subse-
quent refrigerant loss. By programming the cut-
out at slightly below the typical manual cut-out
of 275 PSIG, refrigerant loss due to system
operation problems will be eliminated.
To program the DISCHARGE CUT-OUT, key in the de-
sired 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 200-399 PSIG for this cut-out. For this cut-out
to be functional, the Discharge Pressure Read-out Op-
tion must be installed.
26572A
“PROGRAM” KEY
PROGRAMMING USER PROGRAMMABLE SAFETIES & LIMITS
O U T O F R A N G E
T R Y A G A I N !
D I S C H A R G E C U T O U T
= 3 9 5 P S I G
“PROGRAM”
KEY