SECTION 6 TROUBLE SHOOTING
| SHUTDOWN CAUSE CONTROL CENTER DISPLAY | GOVERNING CONTROL FUNCTION | |||||
| DAY OF WEEK | TIME OF DAY | CAUSEOF SHUTDOWN | METHODOF RESTART | DESCRIPTION | OPERATING POINT | |
| ON RISE | ON FALL | |||||
| MON. | 10:00 AM | Low Water Temperature | Autostart | Low Water (LWT) | Chilled water setpoint | 4°F below chilled water setpoint |
| MON. | 10:00 AM | Low Water Temperature VSD | Autostart | Low Water (LWT) | Chilled water setpoint | 4°F below chilled water setpoint |
| MON. | 10:00 AM | Flow Switch | Autostart | Flow Switch |
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| MON. | 10:00 AM | System Cycling | Autostart | A remote command (computer relay contact or manual switch) |
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| MON. | 10:00 AM | Multi-Unit Cycling | Autostart | (Optional) Lead-Lag Sequence Control |
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| MON. | 10:00 AM | Internal Clock | Autostart | Internal Clock |
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| MON. | 10:00 AM | AC Undervoltage | Autostart | <15% FLA for 25 continuous seconds |
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| MON. | 10:00 AM | Power Fault | Autostart | CM-2 Current Module or Solid State Starter |
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| Remote Stop |
| Energy Management System |
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| MON. |
| Anti-Recycle, 20 Min. Left |
| Anti-Recycle Timer |
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| MON. | 10:00 AM | Low Evap. Pressure |
| Low Evap. Pressure Transducer (LEP) | 5.43 PSIA | 5.42 PSIA |
| MON. | 10:00 AM | Low Evap. Pressure Brine |
| LEP external control (Brine units only) | Set to Job Spec. | Set to Job Spec. |
| MON. | 10:00 AM | Low Oil Pressure |
| Low Oil Press. Transducer (OP) High Oil Press. Transducer (OP) | 20 PSID | 15 PSID |
| MON. | 10:00 AM | High Pressure |
| High Pressure Safety Control (HP) | 15 PSIG | 9 PSIG |
| MON. | 10:00 AM | Evap. Transducer or Probe Error |
| Evap. Pressure Transducer or Leaving Chilled Water Thermistor (RS1) |
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| MON. | 10:00 AM | Motor Controller - Ext. Reset |
| CM-2 or Solid State Starter or Variable Speed Drive |
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| MON. | 10:00 AM | High Discharge Temperature |
| Discharge Temperature Thermistor (RT2) | 220°F | 219°F |
| MON. | 10:00 AM | High Oil Temperature |
| Oil Temperature Thermistor (RT3) | 180°F | 179°F |
| MON. | 10:00 AM | Power Failure | Autostart | Micro Board undervoltage circuit on 5V unregulated supply | 8.29 VDC | 7.84 VDC |
| MON. | 10:00 AM | Power Failure |
| Micro Board undervoltage circuit on 5V unregulated supply | 8.29 VDC | 7.84 VDC |
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PROGRAMMED SETPOINTS BY OPERATOR |
START-UP OF SYSTEM AFTER SHUTDOWN |
PROBABLE CAUSE AND SERVICE REQUIRED |
| 4°F below chilled water setpoint (If set to 40°F would be 36°F.) (36°F minimum) | Automatic Restart when water reaches setpoint. If system is running and setpoint is increased 4°F, system will continue to run, as LWT cutout shifts to a fixed 36°F for 10 minutes. | System load is less than minimum capacity. |
| 4°F below chilled water setpoint (If set to 40°F would be 36°F.) (36°F minimum) | If system is running and setpoint is increased 4°, VSD will Initiate Shutdown. Automatic Restart when water temperature reaches setpoint. | System load is less than minimum capacity. |
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| Automatic Restart when water flow is restored to close flow switch. | Lack of water flow. Check operation of chilled water pump. |
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| Automatic Restart upon remote command. | Contact - connected to the Remote/Local cycling input of the Digital Input Board. |
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| Automatic Restart upon remote command. | Contact - connected to the Multi-Unit cycling input of the Digital Input Board. |
| Daily Schedule programmed to shut down unit. | Will automatically restart when programmed schedule permits. | Pressing Compressor Start Switch overrides the program. |
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| Cycling shutdown occurs when motor current is >15% FLA for 25 seconds during chiller operation. |
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| Will start automatically following coastdown. | Motor Controller contacts opening and closing in less than 3 seconds due to a power fault condition. |
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| Start up by start signal from remote start switch. | Remote Stop Contact Closure. |
| Will not start until 30 minute timer is timed out. | Will restart when time left = 00 minutes. | Minimum time between successive compressor starts is 30 minutes. |
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| To restart, press compressor switch from STOP/RESET to START position. | See OPERATING ANALYSIS, Table 2 Sympton 2. |
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| To restart, press compressor switch from STOP/RESET to START position. | See OPERATING ANALYSIS, Table 2 Sympton 2. |
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| Will restart when pressure increases to 20 PSID. To restart, press compressor switch from STOP/RESET to START position. | See OPERATING ANALYSIS, Table 2 Symptom 4, 5, 6, 7, 9, 10, 11. |
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| Will restart when pressure falls to 9 PSIG. To restart, press compressor switch from STOP/RESET to START position. | See OPERATING ANALYSIS, Table 2 Symptom 1 - High Discharge Pressure. |
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| To restart, press compressor switch from STOP/RESET to START position. | Defective Evap. Pressure Transducer or Leaving Chiller Water thermistor (RS1). LCWT minus saturation temp. is less than -2.5°F or greater than 25°F. Checked every 10 minutes following a 10-min. bypass at start-up. |
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| Reset the device that caused the shutdown. Chiller will start automatically. | CM-2 or Solid State Starter or Variable Speed Drive has shut down chiller. |
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| To restart, press compressor switch from STOP/RESET to START position. | Condenser tubes dirty or scaled or high condenser water temperature. See Symptom 1, Table 2. |
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| To restart, press compressor switch from STOP/RESET to START position. | Dirty oil filter or restricted oil cooler line. Change oil filter. See Sympton 9, Table 2. |
| Optional AUTO Restart Plug is installed on Micro Board. | Will restart automatically when voltage reaches 8.29VDC. An undervoltage circuit on Micro Board monitors the 5VDC unregulated supply for an undervoltage condition. | Power Failure. |
| Auto restart plug is removed on Micro Board. | To restart, press compressor switch to STOP/RESET position and then to START position. | Power Failure. |
TABLE 1 - CAUSES OF NORMAL AND SAFETY SYSTEM SHUTDOWNS IN ACCORDANCE WITH THE MICROCOMPUTER CONTROL CENTER DISPLAY - CONTINUED
| SHUTDOWN CAUsE CONTROL CENTER DISPLAY | GOVERNING CONTROL FUNCTION | |||||
| DAY OF WEEK | TIME OF DAY | CAUSEOF SHUTDOWN | METHODOF RESTART | DESCRIPTION | OPERATING POINT | |
| ON RISE | ON FALL | |||||
| MON. | 10:00 AM | Oil Pressure Transducer Error |
| High Oil Pressure Transducer or Low Oil Pressure Transducer | 60 PSID | 59 PSID |
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| Vane Motor Switch Open | Autostart | Vane Motor Switch |
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| MON. | 10:00 AM | Starter Malfunction Detected |
| Motor Current >15% for 10 seconds with Control Center not calling for motor to run. |
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| MON. | 10:00 AM | Program Initiated Reset | Autostart | Micro Board |
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| Replace RTC-IC Chip Reprogram Setpoints |
| RTC-IC Chip |
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| MON. | 10:00 AM | Low Oil Temperature | Autostart | Oil Temperature Thermistor (RT3) | 71.0°F | 55°F |
| MON. | 10:00 AM | Faulty Discharge Temperature Sensor |
| Discharge Temp. Thermistor (RT2) disconnected or faulty (min. system operating temp. = 32°F) | 30.0°F | 29.9°F |
| MON. | 10:00 AM | Low Line Voltage (SSS units only) |
| SSS Logic Board | See legend on wiring diagram. | |
| MON. | 10:00 AM | Motor Phase Current Unbalance (SSS units only) |
| SSS Logic Board | See Section 2. | |
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PROGRAMMED SETPOINTS BY OPERATOR |
START-UP OF SYSTEM AFTER SHUTDOWN |
PROBABLE CAUSE AND SERVICE REQUIRED |
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| Will start at 59 PSID when compressor switch is placed to STOP/RESET and then START. | This Shutdown is provided to check on Oil pressure Transducers for failure in the high state.Replace Oil PressureTransducer in oil sump or compressor. |
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| Restart automatically after Vane Motor arm linkage is set properly. Press STOP/RESET and then START switch. | Vanes are set improperly. Reset vane linkage, check vane positions using the Service key switch and proper keys on the MicroComputer Control Center or switch of capacity board of Variable Speed Drive. |
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| Press compressor STOP/RESET switch and then START switch. | Check motor starter operation. Motor current value greater than 15%. |
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| Watchdog timer circuit has reset software program. Chiller will automatically restart. |
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| Reprogram the Control Center Setpoints and proceed with Normal Start-up. | Weak Battery. Replace RTC-IC chip U16. |
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| Press STOP/RESET switch and then START switch. | Oil Temperature Thermistor disconnected from Analog Input Board. Reconnect or replace open sensor. |
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| Press STOP/START switch and then START switch. | Faulty Discharge Temperature Thermistor (RT2) or disconnected from Analog Input Board. Connect or replace open sensor. |
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| Chiller will automatically restart when all phases of line voltage increase to the minimum required starting level. | Low AC Line Voltage |
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| Press STOP/RESET switch and then START switch. | Motor Phase Current Unbalance |
TABLE 2 - OPERATING ANALYSIS CHART
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RESULTS |
POSSIBLE CAUSE |
REMEDY |
1. SYMPTOM: ABNORMALLY HIGH DISCHARGE PRESSURE
| Temperature difference between liquid refrigerant out and water off condenser higher than normal. | Air in condenser. | Purge unit operates automatically to take care of this condition. Test for air leaks if display reads: WARNING – EXCESS PURGE |
| High discharge pressure. | Condenser tubes dirty or scaled. | Clean condenser tubes. Check water conditioning. |
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| High condenser water temperature. | Reduce condenser water inlet temperature. (Check cooling tower and water circulation.) |
| Temperature difference between condenser water on and water off higher than normal, with normal cooler pressure. | Insufficient condensing water flow. | Increase the quantity of water through the condenser to proper value. |
2. SYMPTOM: ABNOrMALLY LOW SUCTION PRESSURE
| Temperature difference between leaving chilled water and refrigerant in cooler greater than normal with high discharge temperature. | Insufficient charge of refrigerant. | Check for leaks and charge refrigerant into system. |
| Flow orifice blocked. | Remove obstruction. | |
| Temperature difference between leaving chilled water and refrigerant in the cooler greater than normal with normal discharge temperature. | Cooler tubes dirty or restricted. | Clean cooler tubes. |
| Temperature of chilled water too low with low motor amperes. | Insufficient load for system capacity. | Check prerotation vane motor operation and setting of low water temperature cutout. |
3. SYMPTOM: HIGH COOLER PRESSURE
| High chilled water temperature. | Prerotation vanes fail to open. | Check the prerotation vane motor positioning circuit. |
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| System overloaded. | Be sure the vanes are wide open (without overloading the motor) until the load decreases. |
4. SYMPTOM: NO OIL PRESSURE WHEN SYSTEM START BUTTON PUSHED
| Low oil pressure displayed on control center; compressor will not start. | Oil pump running in wrong direction. | Check rotation of oil pump. (Electrical Connections) |
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| Oil pump not running. | Check electrical connecrtions to oil pump and press manual reset on oil pump starter (on condenser shell in front of purge unit). |
5. SYMPTOM: COMPRESSOR STARTS, NORMAL OIL PRESSURE DEVELOPS, FLUCTUATES FOR SHORT WHILE, THEN COMPRESSOR STOPS ON OIL PRESSURE CUTOUT
| Oil pressure normal, fluctuates, then com- pressor stops on Oil Pressure Cutout. | Unusual starting conditions exist, i.e., oil foaming in reservoir and piping due to lowered system pressure. | Drain the oil from the compressor and charge new oil into the compressor. (See “Oil Charging Procedure”, page 44.) | ||
| Display reading: | LOW OIL PRESSURE |
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| Burned out oil heater. | Replace oil heater. | |
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RESULTS |
POSSIBLE CAUSE |
REMEDY |
6. SYMPTOM: UNUSUALLY HIGH OIL PRESSURE DEVELOPSWHEN OIL PUMP RUNS
| Unusually high oil pressure is displayed when the oil pressure display key is pressed when the oil pump is running. | High oil pressure. Transducer defective. Relief valve is misadjsuted. | Replace low or high oil pressure transducer. Adjust external relief valve. |
7. SYMPTOM: OIL PUMP VIBRATES OR IS NOISY
| Oil pump vibrates or is extremely noisy with some oil pressure when pressing “Oil Pressure” display key. | Misalignment of pump or piping. Mounting bolts loose. Bent shaft. Worn pump parts. | Correct condition or replace faulty part. |
| NOTE: When oil pump is run without an oil supply it will vibrate and become extremely noisy. | Oil not reaching pump suction inlet in sufficient quantity. | Check oil supply and oil piping. |
8. SYMPTOM: OIL PRESSURE GRADUALLY DECREASES (NOTED BY OBSERVATION OF DAILY LOG SHEETS)
| Oil pressure (noted when pressing “Oil Pressure” display key) drops to 70% of oil pressure when compressor was originally started. | Oil filter is dirty. | Change oil filter. |
| Extreme bearing wear. | Inspect compressor. |
9. SYMPTOM: OIL RETURN SYSTEM CEASESTO RETURN AN OIL/REFRIGERANT SAMPLE
| Oil refrigerant return not functioning. | Filter-drier in oil return system dirty. | Replace oil filter-drier with new. |
| Jet or office of oil return jet clogged. | Remove jet, inspect for dirt. Remove dirt using solvent and replace. |
10. SYMPTOM: OIL PUMP FAILS TO DELIVER OIL PRESSURE
| No oil pressure registers when pressing “Oil Pressure” display key when oil pump runs. | Faulty oil pressure transducer. Faulty writing/connectors. | Replace oil pressure transducer. |
11. SYMPTOM: REDUCED OIL PUMP CAPACITY
| Oil pump pumping capacity low. | Excessive end clearance in pump. Other worn pump parts. | Inspect and replace worn parts. |
| Partially blocked oil supply inlet. | Check oil inlet for blockage. |
12. SYMPTOM: IMPROPER PURGE UNIT OPERATION
| Purge unit not purging and air is present in the unit. |
| Check these components and replace where necessary. |
| Purge unit purging air and refrigerant |
| Restore refrigerant liquid cooling supply. |
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