Specifications

100
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 primary and secondary
message lines on the ICVC default screen (Fig. 15). These
messages will indicate where the fault is occurring. These mes-
sages contain the alarm message with a specified code. This
code or state appears with each alarm and alert message. The
ALARM and ALERT HISTORY tables on the ICVC SER-
VICE menu also contain an alarm or alert message to further
expand on the alarm or alert. For a complete list of possible
alarm messages, see Table 17. If the alarm light starts to flash
while accessing a menu screen, press the softkey to re-
turn to the default screen to read the alarm message. The STA-
TUS 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 18A and 18B.
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 18A and 18B. 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 18A or 18B 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.
CHECK SENSOR ACCURACY — Place the sensor in a
medium of known temperature and compare that temperature
to the measured reading. The thermometer used to determine
the temperature of the medium should be of laboratory quality
with 0.5 F (0.25 C) graduations. The sensor in question
should be accurate to within 2 F (1.2 C).
See Fig. 2 for sensor locations. The sensors are immersed
directly in the refrigerant or water circuits. When installing a
new sensor, apply a pipe sealant or thread sealant to the sensor
threads.
An additional thermistor, factory installed in the bottom of
the cooler barrel, will read as EVAPORATOR REFRIGERANT
TEMP on the HEAT_EX display screen. This thermistor pro-
vides additional protection against a loss of water flow.
DUAL TEMPERATURE SENSORS — For servicing con-
venience, there are 2 sensors each on the bearing and motor
temperature sensors. If one of the sensors is damaged, the other
can be used by simply moving a wire. The number 2 terminal
in the sensor terminal box is the common line. To use the sec-
ond sensor, move the wire from the number 1 position to the
number 3 position.
Checking Pressure Transducers — There are 4
factory-installed pressure transducers measuring refrigerant
and oil pressure. There is a fifth pressure transducer measuring
pressure variations at the compressor discharge on compressors
equipped with a split ring diffuser (SRD). This transducer is
not displayed and does not require calibration.
Except for the discharge transducer, these transducers
can be calibrated if necessary. It is not usually necessary to
calibrate at initial start-up. However, at high altitude loca-
tions, it is necessary to calibrate the transducers to ensure the
proper refrigerant temperature/pressure relationship. Each
transducer is supplied with 5 vdc power from the CCM. If the
power supply fails, a transducer voltage reference alarm oc-
curs. If the transducer reading is suspected of being faulty,
check the TRANSDUCER VOLTAGE REF supply voltage. It
should be 5 vdc ± 0.5 v displayed in CONTROL TEST under
CCM Pressure Transducers. If the TRANSDUCER VOLT-
AGE REF supply voltage is correct, the transducer should be
recalibrated or replaced.
Also check that inputs on the CCM J5-1 through J5-6 have
not been grounded and are not receiving anything other than a
4 to 20 mA signal.
TRANSDUCER REPLACEMENT — Since the transducers
are mounted on Schrader-type fittings, there is no need to re-
move refrigerant from the vessel when replacing the transduc-
ers. Disconnect the transducer wiring. Do not pull on the trans-
ducer wires. Unscrew the transducer from the Schrader fitting.
When installing a new transducer, do not use pipe sealer
(which can plug the sensor). Put the plug connector back on the
sensor and snap into place. Check for refrigerant leaks.
COOLER AND CONDENSER PRESSURE TRANS-
DUCER AND OPTIONAL WATERSIDE FLOW DEVICE
CALIBRATION — Calibration can be checked by comparing
the pressure readings from the transducer to an accurate refrig-
eration gage reading. These readings can be viewed or cali-
brated from the HEAT_EX screen on the ICVC. The
transducer can be checked and calibrated at 2 pressure points.
These calibration points are 0 psig (0 kPa) and between 25 and
250 psig (173 and 1724 kPa). To calibrate these transducers:
1. Shut down the compressor, cooler, and condenser pumps.
NOTE: There should be no flow through the heat
exchangers.
2. Disconnect the transducer in question from its Schrader
fitting for cooler or condenser transducer calibration. For
oil pressure or flow device calibration, leave the transduc-
er in place.
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
WARNING
Be sure to use a back-up wrench on the Schrader fitting
whenever removing a transducer, since the Schrader fitting
may back out with the transducer, causing a large leak and
possible injury to personnel.
(continued on page 117)