Carrier 17DA Start-up, Operation And Maintenance Instructions Manual

Also see for 17DA: Start-up instructions Application data Operating and maintenance instructions Start-up instructions

22Chilled Water Temperature Too Low withCompressor RunningCHILLED WATER SET POINT IN THE PLC SET TOOLOW — Correct set point and check for overrides from thebuilding control system.LOW COOLING LOAD — The compressor cannot unloadcompletely. If there is so little load that the guide vanes closefully, then the water temperature will continue to drop until therecycle function or chilled water low-temperature safety stopsthe machine.INACCURATE THERMISTOR — The reading on the pan-el will not coincide with other sensors monitoring the leavingchilled water.SENSORS OUTSIDE OF THE CHILLER CONTROLSARE INACCURATE — The machine sensor could be correctand other sensor(s) are out of calibration.GUIDE VANES NOT CLOSING• Check pressure of supply air and cushion air pressure.• Confirm that the air signal from the transducer matches thesignal output from the PLC.• Calibrate the positioner.• Test the actuator for leakage past the piston seal.Refrigerant Temperature Too LowCOOLER WATERBOX DIVISION PLATE GASKET OUTOF PLACE — Fix gasket.LOW REFRIGERANT CHARGE — When the machine canbe stopped, allow time for liquid to flow to the cooler. Comparethe liquid level with the charging mark on the cooler levelsightglass. Add refrigerant if required.Check for leaks and check shutdown seal operation. Test re-frigerant alarm sensors.Leaving Chilled Water Temperature FluctuatesRETURN CHILLED WATER TEMPERATURE FLUCTU-ATING FASTER THAN CONTROLS CAN RESPOND —Adjust controls.CAPACITY CONTROL IN PLC NEEDS ADJUST-ING — Adjust capacity controls.GUIDE VANES MOVING ERRATICALLY• Check actuator (see Guide Vanes Not Closing sectionabove)• With machine not running, disconnect the actuator andmove the guide vanes manually. There should be a resis-tance, easily overcome, at the point where the discharge dif-fuser starts opening or closing. Check for obstructions.Condenser Pressure Too HighLOW WATER FLOW OR HIGH WATER TEMPERA-TURE — Check the following:• Check condensing water pump for proper operation.• Check delta P and delta T across the condenser water side todetermine if there is bypassing around the division plate.• Check delta P across the condenser water pump.• Check cooling tower controls and fans. Check to see iftower bypass is open.• Check for correct level in the cooling tower.• Check flow meter readings.• If the condenser water valves automatically regulate con-denser flow, check the control settings and valve operation.• Ensure that condenser water strainers are clean.AIR IN THE CONDENSER — Air or other non-condens-able gases in the condenser will cause a rise in normal condens-ing pressures. Because of the subcooler, true condensing tem-peratures cannot be determined. If the subcooler level is set ac-cording to the method in the Charge Refrigerant section, thenthe actual condensing temperature will be close to thetemperature at the subcooler inlet thermowell. This is locatedadjacent to the level control/transmitter.If air is suspected, then check the purge. See the Purge Cy-cle section on page 19.FOULED CONDENSER TUBES — Check for fouled or ob-structed tubes. Clean as required.Oil Pressure Too LowPLUGGED FILTERS — Switch to alternate filter cartridge.Replace plugged filter.PRESSURE REGULATOR SET TOO LOW — Adjust asrequired.FAULTY PRESSURE REGULATOR — Replace regulator.FAULTY PUMP OR MOTOR — Replace faulty component.Oil Pressure Too HighPRESSURE REGULATOR SET TOO HIGH — Adjust asrequired.RESTRICTION IN PRESSURE SENSING LINE —Check pressures and temperatures throughout lubrication sys-tem. Correct as required.Oil Reservoir Temperature Too LowEXCESSIVE WATER FLOWING THROUGH OILCOOLER• Adjust water flow.• If equipped with an automatic regulator, adjust theregulator.• Check for good thermal contact between the regulator sens-ing bulb and the oil line leaving the oil cooler. Check thecapillary tube for damage.• Replace the regulator if faulty.Oil Reservoir Temperature Too HighINSUFFICIENT WATER FLOW THROUGH OILCOOLER• Adjust water flow.• If equipped with an automatic regulator, then adjust theregulator.• Check for good thermal contact between the regulator sens-ing bulb and the oil line leaving the oil cooler. Check thecapillary tube for damage. Check for contamination plug-ging the regulator valve.• Replace the regulator if faulty.FOULED OR OBSTRUCTED OIL COOLERTUBES — Check oil cooler. Clean if necessary.TEMPERATURE OF OIL RETURNING FROM BEAR-INGS TOO HIGH — Check for bearing wear, in particularthe thrust bearing. Check the bearings for foreign particles orany indication of wiping.A bad bearing can cause extensive damage to machine. Besure to diagnose and correct reasons for overheated bearingsbefore restarting the machine.Compressor Discharge Gas Temperature TooHighEXTREMELY LOW LOAD — Verify low load condition.Add load to machine if possible.LOW COOLER REFRIGERANT LEVEL — Insufficientcharge in the machine or condenser refrigerant level too high.EXCESSIVE TRAVEL OF DIFFUSER THROTTLINGRING — This can only be determined through compressordisassembly.CONTROLSSafety Controls — Safety controls come in multipleforms. Safety functions are programmed into the PLC which