Carrier 19XRV Start-up, Operation And Maintenance Instructions Manual

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Carrier 19XRV Start-up, Operation And Maintenance Instructions Manual Manual pdf 79 page image

TROUBLESHOOTING GUIDE(Tables 15-18B)Overview- The PIC III has many features to help tileoperator and technician troubleshoot a 19XRV 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 continueto show current information. Once all alarms have beencleared (by correcting the problems and pressing thesoftkey), the ICVC default screen returns tonormal operation.• The CONTROL ALGORITHM STATUS screens (whichinclude the CAPACITY. OVERRIDE, LL_MAINT.VFD_HIST. LOADSHED, CUR_ALARM, WSM-DEFME, and OCCDEFCM screens) display informationthat helps to diagnose problems with chilled watertemperature control, chilled water temperature controloverrides, hot gas bypass, surge algorithm status, andtime schedule operation. See Table 15.• The control test feature facilitates the proper operationand test of temperature sensors, pressure transducers, theguide vane actuator, oil pump, water pumps, towercontrol, and other on/off outputs while the compressor isstopped. It also has the ability to lock off the compressorand turn on water pumps for pumpout operation. TheICVC shows the temperatures and pressures requiredduring these operations.• From other SERVICE tables, the operator/technician canaccess 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 moredetailed message -- along with a diagnostic message --is also stored into the ALARM HISTORY and ALERTH[STORY tables.• Review the ALERT HISTORY table to view other lesscritical events and abnormal conditions which may haveoccurred. Compare timing of relevant alerts and alarms.Checking Display Messages--The first area tocheck when troubleshooting the 19XRV is the ICVC display. Ifthe alarm light is flashing, check the primary and secon&wymessage lines on the ICVC default screen (Fig. 14). Thesemessages will indicate where the fault is occurring. Thesemessages contain the alarm message with a specified code.This code or state appears with each alarln and alert message.The ALARM and ALERT HISTORY tables on the [CVCSERVICE menu also contains a message to further expand onthe fault description.NOTE: The &_te format in these tables is MM/DD/YY.For a complete list of possible _darm and alert messages, seeTable 15. If the alarm light starts to flash while accessing amenu screen, press the _ softkey to return to the defimltscreen to read the almm message. The STATUS screen can alsobe accessed to determine where an alarm exists.A "C" to the right ofa pammeter's value means that there isa communications fault on that channel.Checking Temperature Sensors --All temperaturesensors are thermistor-type sensors. This means that theresistance of the sensor varies with temperature. All sensorshave the same resistance characteristics. If the controls m'e on,determine sensor temperature by measuring voltage diop; if thecontrols are powered off, detemfine sensor temperature bymeasuring resistance. Compare the readings to the values listedin Table 18A or 18B.RESISTANCE CHECK -- Turn off the control power and,fi_)m the module, disconnect the terminal plug of the sensor inquestion. With a digital ohmmetel: measure sensor resistancebetween receptacles as designated by the wiring diagram. Theresistance and corresponding temperature are listed inTable 18A or 18B. Check the resistance of both wires toground. This resistance should be infinite.VOLTAGE DROP -- The voltage drop across any energizedsensor can be measured with a digital voltmeter while thecontrol is energized. Table 18A or 18B lists the relationshipbetween temperature and sensor voltage drop (volts dcmeasmed across the energized sensor). Exercise ctue whenmeasuring voltage to prevent damage to the sensor leads,connector plugs, and modules. Sensors should also be checkedat the sensor plugs. Check the sensor wire at the sensor for5 vdc if the control is powered on.Relieve all refrigerant pressure or &'ain the water beforereplacing temperature sensors or thermowells threaded intothe refrigerant pressure boundary. Failure to do so couldresult in persomd injmy and equipment damage.CHECK SENSOR ACCURACY-- Place the sensor in amedium of known temperature and compare that temperatmeto the measured reading. The thermometer used to determinethe temperature of the medium should be of laboratory qu_flitywith 0.5 ° F (.25 ° C) graduations. The sensor in question shouldbe accurate to within 2 ° F (1.2 ° C).See Fig. 7 for sensor locations. The sensors are immerseddirectly in the refrigerant or water circuits. The wiring at eachsensor is easily disconnected by unlatching the connectol:These connectors allow only one-way connection to the sensol:When installing a new sensor, apply a pipe sealant or threadsealant to the sensor threads.DUAL TEMPERATURE SENSORS -- For servicing con-venience, there are 2 sensol_ each on the beming and motortemperature sensors. If one of the sensors is &_maged, the othercan be used by simply moving a wire. The number 2 terminalin the sensor terminal box is the common line. To use thesecond sensol: move the wire from the number I position to thenumber 3 position.Checking Pressure Transducers-- There are 6factoly-installed pressure transducers, with inputs available foroptional cooler and condenser watel.side differential pressuretransducers. The ICVC softwm'e will display a default readingof 26 psi during start-up and operation. An additional transduc-er. factory inst;_lled in the bottom of the cooler barrel, will readas EVAPORATOR SATURATION TEMP on the HEAT_EXDISPLAY screen. This provides additional protection against aloss of water flow condition.These pressure transducers can be calibrated if necessary. Itis not usually necessary to calibrate at initial start-up.However. at high altitude locations, it is necessmy to calibratethe transducel.'s to ensure the proper refrigerant temperature/pressure relationship. Each transducer is supplied with 5 vdcpower from the CCM. If the power supply fifils, a transducervoltage reference alarm occurs. If the transducer reading issuspected of being faulty, check the TRANSDUCER VOLT-AGE REF supply voltage. It should be 5 vdc _+.5v displayed inCONTROL TEST under CCM PRESSURE TRANSDUC-ERS. If the TRANSDUCER VOLTAGE REF is correct, thetransducer should be recalibrated or replaced.Also check that inputs on CCM J5-1 through J5-6 have notbeen grounded and are not receiving anything other than a 4 to20 mA signal.79