JOHNSON CONTROLS
138
FORM 160.79-O3
ISSUE DATE: 11/09/2018
SECTION 2 – OPTIVIEW CONTROL CENTER
ing upon Control Center configuration. It indicates a
cycling shutdown when displayed in orange charac-
ters; Safety shutdown when displayed in red charac-
ters. The Control Center is configured for auto-restart
or manual restart after power failure by a qualified Ser-
vice Technician.
“LEAVING CHILLED LIQUID – FLOW SWITCH
OPEN”
The Chilled Liquid Flow Switch has remained open for
2 continuous seconds while the chiller was running or
failed to close during the System Pre-lube period. The
chiller will automatically restart when the flow switch
closes.
“CONDENSER – FLOW SWITCH OPEN”
The Condenser water flow switch has remained open
for 30 continuous seconds while the chiller was run-
ning. This check is bypassed for the first 30 seconds
of “System Run”. The chiller will automatically restart
when the flow switch closes.
Safety Shutdown Messages
“EVAPORATOR – LOW PRESSURE”
The evaporator pressure, as sensed by the Evapora-
tor Transducer, has decreased to the Safety shutdown
threshold. For water cooling applications, the safety
shutdown threshold is a fixed value for the respective
refrigerant. For Brine cooling applications, the safety
shutdown threshold varies according to the concentra-
tion of the Brine solution. The Brine shutdown thresh-
old is programmed at the YORK Factory. It should not
be changed by anyone other than a qualified Service
Technician. The chiller can be started after the evapo-
rator pressure increases to the restart threshold and the
Operator presses the Clear Faults button.
SHUTDOWN
(PSIG)
RESTART (PSIG)
WATER
COOLING
R134A
25.0
25.1
BRINE
COOLING
R134A
6.0 to 25.0
as programmed
+0.1 >
Shutdown
threshold
“EVAPORATOR – LOW PRESSURE - SMART
FREEZE”
Smart Freeze protection is activated and has shutdown
the chiller because the evaporator temperature has
been below the Smart Freeze threshold for greater than
the allowable number of seconds. If the Evaporator
Refrigerant Temperature sensor RT7 is Enabled. This
parameter is used as the evaporator refrigerant temper-
ature and the freeze threshold is 32.8°F. If RT7 is not
enabled, the evaporator refrigerant temperature used is
the Evaporator Saturation Temperature, derived from
the Evaporator Pressure Transducer and the freeze
threshold is 34.0°F.
The total count is incremented once for every sec-
ond the evaporator refrigerant temperature is below
the freeze threshold (but is never decremented below
zero). The number of seconds it will take the chilled
liquid to freeze is based on how far the evaporator re-
frigerant temperature is below the freeze threshold as
follows:
# seconds to freezing = (4053.7) / (freeze threshold –
evap. refrigerant temp.)
Smart Freeze is activated only if the feature has been
Enabled by a Service technician and
the Leaving
Chilled Liquid
temperature Setpoint is <38.0°F.
“EVAPORATOR – TRANSDUCER OR LEAVING
LIQUID PROBE”
A possible defective Evaporator pressure Transducer
or Leaving Chilled Liquid temperature Thermistor has
been detected. The pressure and temperature that these
devices are indicating are not in the correct relation-
ship to each other. The Control Center converts the
evaporator pressure to a Saturated Temperature value
and compares this value to the Leaving Chilled Liquid
temperature (difference = chilled liquid temp – evap-
orator saturated temp). The difference should not be
outside the range of –2.5°F to +25.0°F. If the Trans-
ducer and Thermistor are accurate, the Evaporator
Saturated temperature should not be > 2.5°F warmer
nor > 25.0°F colder than the leaving chilled liquid tem-
perature. In order to initiate a shutdown, the difference
must be outside the acceptable range continuously for
10 minutes. The chiller can be started after the Opera-
tor presses the Clear Faults button.
