JOHNSON CONTROLS
126
FORM 160.69-O1
ISSUE DATE: 9/30/2012
SECTION 2 – OPTIVIEW CONTROL CENTER
“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 2 continuous seconds (30 seconds with software
version C.OPT.11.03.01.004 (and later) while the chill-
er was running. This check is bypassed for the first 30
seconds of “System Run”. The chiller will automati-
cally 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 following instructions in YORK Service
Manual 160.69-M1. The chiller can be started after the
evaporator pressure increases to the restart threshold
and the COMPRESSOR switch is placed in the Stop-
Reset (O) position.
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 shut-
down the chiller because the evaporator temperature
has been below the Smart Freeze threshold for greater
than the allowable number of seconds. If the Evapo-
rator Refrigerant Temperature sensor RT7 is Enabled,
(using procedure in Service Manual 160.69-M1), 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 (following instruc-
tions in Service Manual 160.69-M1) 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 – evapo-
rator saturated temp). The difference should not be out-
side the range of –2.5°F to +25.0°F. If the Transducer
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 temperature. In
order to initiate a shutdown, the difference must be
outside the acceptable range continuously for 10 min-
utes. The chiller can be started after the COMPRES-
SOR switch is placed in the Stop-Reset (O) position.
“EVAPORATOR – TRANSDUCER OR TEMPER-
ATURE SENSOR”
A possible defective Evaporator pressure Transducer
or Refrigerant Temperature Sensor has been detected.
The Control Center converts the evaporator pressure to
a Saturated Temperature value and compares this val-
ue to the optional Evaporator Refrigerant Temperature
Sensor. If the difference between these temperatures
is greater than 3.0°F, continuously for 1 minute, this
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