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99
TROUBLESHOOTING GUIDE
Overview —
The PIC II has many features to help the op-
erator and technician troubleshoot a 19XR chiller.
• The ICVC shows the chiller’s actual operating condi-
tions and can be viewed while the unit is running.
• The ICVC default screen freezes when an alarm occurs.
The freeze enables the operator to view the chiller condi-
tions at the time of alarm. The STATUS screens continue
to show current information. Once all alarms have been
cleared (by correcting the problems and pressing
the
softkey), the ICVC default screen returns to
normal operation.
• The CONTROL ALGORITHM STATUS screens (which
include the CAPACITY, OVERRIDE, SURGPREV,
LL_MAINT, ISM_HIST, LOADSHED, CUR_ALARM,
WSMDEFME, and OCCDEFCM screens) display infor-
mation that helps to diagnose problems with chilled
water temperature control, chilled water temperature
control overrides, hot gas bypass, surge algorithm status,
and time schedule operation.
• The control test feature facilitates the proper operation
and test of temperature sensors, pressure transducers, the
guide vane actuator, diffuser actuator (if equipped), oil
pump, water pumps, tower control, and other on/off out-
puts while the compressor is stopped. It also has the abil-
ity to lock off the compressor and turn on water pumps
for pumpout operation. The ICVC shows the tempera-
tures and pressures required during these operations.
• From other SERVICE tables, the operator/technician can
access configured items, such as chilled water resets,
override set points, etc.
• If an operating fault is detected, an alarm message is gen-
erated and displayed on the ICVC default screen. A more
detailed message — along with a diagnostic message —
is also stored into the ALARM HISTORY table.
• Review the ALERT HISTORY table to view other less
critical events which may have occurred. Compare tim-
ing of relevant events and alarms.
Checking Display Messages —
The first area to
check when troubleshooting the 19XR is the ICVC display. If
the alarm light is flashing, check the chiller primary and sec-
ondary message lines on the ICVC default screen (Fig. 17).
These messages will indicate where the fault is occurring.
These messages contain the alarm message with a specified
code. This code or state appears with each alarm and alert mes-
sage. The ALARM and ALERT HISTORY tables on the ICVC
SERVICE menu also contain an alarm or alert message to fur-
ther expand on the alarm or alert. For a complete list of possi-
ble alarm messages, see Table 16. If the alarm light starts to
flash while accessing a menu screen, press the
softkey to
return to the default screen to read the alarm message. The
STATUS screen can also be accessed to determine where an
alarm exists.
A “C” to the right of a parameter’s value means that there is
a communications fault on that channel.
Checking Temperature Sensors —
All tempera-
ture sensors are thermistor-type sensors. This means that the re-
sistance of the sensor varies with temperature. All sensors have
the same resistance characteristics. If the controls are on, deter-
mine sensor temperature by measuring voltage drop; if the con-
trols are powered off, determine sensor temperature by measur-
ing resistance. Compare the readings to the values listed in
Tables 17A and 17B.
RESISTANCE CHECK — Turn off the control power and,
from the module, disconnect the terminal plug of the sensor in
question. With a digital ohmmeter, measure sensor resistance
between receptacles as designated by the wiring diagram. The
resistance and corresponding temperature are listed in
Tables 17A and 17B. Check the resistance of both wires to
ground. This resistance should be infinite.
VOLTAGE DROP — The voltage drop across any energized
sensor can be measured with a digital voltmeter while the con-
trol is energized. Table 17A or 17B lists the relationship be-
tween temperature and sensor voltage drop (volts dc measured
across the energized sensor). Exercise care when measuring
voltage to prevent damage to the sensor leads, connector plugs,
and modules. Sensors should also be checked at the sensor
plugs.
RESET
CAUTION
Relieve all refrigerant pressure or drain the water before
removing any thermowell threaded into the refrigerant
pressure boundary. Failure to do so could result in personal
injury and equipment damage.
EXIT
continued on page 116.
Summary of Contents for AquaEdge 19XR series
Page 69: ...69 Fig 33 19XR Leak Test Procedures a19 1625 ...
Page 154: ...154 Fig 64 Benshaw Inc Wye Delta Unit Mounted Starter Wiring Schematic Low Voltage a19 1873 ...
Page 161: ...161 Fig 69 Typical Low Voltage Variable Frequency Drive VFD Wiring Schematic 575 v ...
Page 162: ...162 Fig 69 Typical Low Voltage Variable Frequency Drive VFD Wiring Schematic 575 v cont ...
Page 186: ...186 APPENDIX B LEAD LAG WIRING 19XR Lead Lag Schematic Series Cooler Flow a19 1655 ...
Page 187: ...187 APPENDIX B LEAD LAG WIRING cont 19XR Lead Lag Schematic Parallel Cooler Flow a19 1717 ...