York YST Operation Manual page 141

FORM 160.67-O1
ISSUE DATE: 4/1/2015
" 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
relationship 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
– evaporator saturated temp). The difference should
not be outside 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 minutes after the chiller is running
at or above the minimum rated speed. The chiller can
be started after the START/STOP control switch is
placed in the STOP-RESET (O) position.
" evaporator – Transducer or Temperature
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 value to
the optional Evaporator Refrigerant Temperature Sensor.
If the difference between these temperatures is greater
than 3.0°F, continuously for 1 minute, this shutdown
is performed. This check is only performed under the
following conditions:
• Chiller has been running for at least 10 minutes
• Evaporator Refrigerant Temperature Sensor has
been enabled by a Service technician using in-
structions in YORK Service Manual 160.67.M2
• Not in Brine cooling mode
• Smart Freeze is enabled
• Evaporator Temperature Sensor or Evaporator
Saturation Temperature is indicating a tempera-
ture of <32.0°F.
The chiller can be started after the temperatures are
within 3.0°F of one another and the START/STOP con-
trol switch is placed in the STOP-RESET (O) position.
JOHNSON CONTROLS
SECTION 2 - OPTIVIEW CONTROL CENTER INTRODUCTION
" Condenser – high pressure Contacts open"
The contacts of the electro-mechanical high pressure
safety device, have opened because this device has de-
tected a pressure >180.0 PSIG (R134a) >265.0 (R22).
The contacts will automatically close when the con-
denser pressure decreases to <120.0 PSIG (R134a) <
205 PSIG (R22). The chiller can be started after the
contacts close and the START/STOP control switch is
placed in the STOP-RESET (O) position.
"Condenser – high pressure"
The condenser pressure, as sensed by the Condenser
Transducer, has increased to >180.0 PSIG (R134a),
>265.0 PSIG (R22). The chiller can be started after
the pressure decreases to < 120.0 PSIG (R134a), < 205
PSIG (R22) and the START/STOP control switch is
placed in the STOP-RESET (O) position.
" Condenser – pressure Transducer out of
range"
The Condenser Pressure Transducer is indicating
a pressure that is < 6.8 PSIG (R134a), < 24.2 PSIG
(R22) or > 300.0 PSIG (R134a or R22). This is outside
the normal operating range of the transducer. This is
generally indicates a defective transducer. The chiller
can be started after the transducer is indicating a pres-
sure that is within range and the START/STOP control
switch is placed in the STOP-RESET (O) position.
"auxiliary Safety – Contacts Closed"
The Auxiliary Safety shutdown contacts, connected to
I/O Board TB4-31 have closed, initiating a safety shut-
down. This input is a general-purpose, user defined
safety shutdown input. The chiller can be started after
the contacts open and the START/STOP control switch
is placed in the STOP-RESET (O) position.
" Compr discharge – high Temperature"
The discharge temperature, as sensed by the Discharge
Temperature Thermistor, has increased to > 220.0°F.
The chiller can be started after the temperature de-
creases to < 220.0°F and the START/STOP control
switch is placed in the STOP-RESET (O) position.
" Compr discharge – low Temperature"
The discharge temperature, as sensed by the Discharge
Temperature Thermistor, has decreased to < 30.0°F.
The chiller can be started after the temperature increas-
es to > 30.0°F and the START/STOP control switch is
placed in the STOP-RESET (O) position.
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