York YCAS0295EB, Installation Operation & Maintenance

Page: 132 / 194

132 YORK INTERNATIONAL
FORM 201.19-NM7 (804)
The U13 RTC chip should be re placed as soon as
pos si ble with Part # 031-00955-000. Otherwise, the
chill er will shutdown and lose all programmed points,
and re quire a MANUAL OVERRIDE restart, if a power
fail ure occurs.
Pump Down:
This message indicates that both refrigerant systems are
in a pumpdown cycle. Pumpdown display mes sag es oc-
cur on shutdowns where the cool ing load has been met,
or when a sys tem switch is turned OFF. Note that only
one com pres sor could be pump ing down, as shown in
the following display:
See Section 1.18 (page 126) for details of pumpdown
con trol.
When this message appears, the chiller will not run and
the Unit Switch must be cycled OFF and ON to start
the unit.
Incorrect Unit Type Warning:
The incorrect Unit Type Warning will occur if the DIP
Switch setting for unit type and the type programmed
into the micro "at the factory" are not the same. This
message will be displayed until the "factory" pro-
grammed unit type and DIP Switch setting agree. See
Page 173 for Service Mode Programming.
2.4 ANTICIPATION CONTROL STATUS
MESSAGES
Anticipation controls are built into the soft ware to
pre vent safety shutdowns by automatically overriding
the temperature controls, if system conditions approach
safe ty thresholds. This avoids total loss of cooling
re sult ing from a lockout by a safety control.
Anticipation controls monitor discharge pressure, mo tor
current and suction temperature for each com pres sor
and if maximum limits are approached, the slide valve
loading of the respective compressor will be re duced to
avoid exceeding the limit.
Displays of anticipation safety control messages and
their meanings are as follows:
Discharge Pressure Limiting:
Discharge Pressure Limiting takes effect when
com pres sor discharge pressure nears the point at which
the high pressure cutout would shut the system down.
When the above message appears, discharge pressure
has ex ceed ed the programmable threshold and the
com pres sor is being unloaded in an effort to prevent
shutdown on the high pressure cutout. The operation of
this safe ty is important if condenser coils become dirty,
if there is a problem with the condenser fan operation,
or if ex treme ambient or load conditions occur.
See
Anticipatory Unloading Controls Page 155 for detailed
operation.
Incorrect Refrigerant Warning:
The incorrect Refrigerant Warning will occur if the
DIP Switch setting for refrigerant type and the type
pro grammed into the micro “at the factory” under the
Service Mode are not the same. This message will be
displayed until the non-pro gram ma ble “factory” pro-
grammed refrigerant type and DIP Switch setting agree.
See Page 173 for Service Mode programming.
Power Failure Warning:
The Power Failure Warning will only be displayed on
“power restoration” after a “power loss,” if manual re-
start on power failure is se lect ed under the PRO GRAM
key (page 164). If manual restart on pow er failure has
been selected, the following warning mes sage is dis-
played indefi nitely on power res to ra tion and the chiller
will not run until the UNIT Switch is cy cled OFF-and-on
to re start the unit. This safety is available for users who
de sire a chiller lock-out on pow er failure.
This is typically not a desirable
feature to select. Most applications re-
quire auto-reset after a power failure.
Therefore, "Automatic" is typically
selected and programmed under the
PROGRAM key. See page 164.
R E P R O G R A M T Y P E O F
R E F R I G E R A N T T O R U N
! ! P O W E R F A I L U R E ! !
C Y C L E U N I T S W I T C H
S Y S # D S C H L I M I T I N G
S Y S # D S C H L I M I T I N G
S Y S 1 P U M P I N G D O W N
S Y S 2 C O M P R U N N I N G
S Y S 1 P U M P I N G D O W N
S Y S 2 P U M P I N G D O W N
Micro Panel Contents
R E P R O G R A M
U N I T T Y P E