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TROUBLESHOOTING
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The following table shows efficient checking procedures for trouble.
Fault
Possible Cause
Check/Corrective Action
Excessively Low Chilled water Outlet
Temperature
1. Check for excessively low setting of the
chilled water setting knob.
Defective Thermistor
1. Check for malfunction of the thermistor.
Replace, if necessary.
Shortage of Chilled Water Flow
1. Check the rotation of the pump.
Compressor Stops on Freeze
Protection Thermostat
Air in water Circuit
1. Purge air.
High or Low Voltage, Single-Phase or Phase
Imbalance
1. Check the power supply line and contactor.
Repair, if necessary.
Excessive Superheat
1. Check for refrigerant leakage and faulty
solenoid valve for liquid bypass.
Defective Element
1. Check the contact of the internal
thermostat during the cold condition.
Compressor Stops on Internal
Thermostat or Discharge Gas
Thermostat
Excessive High Discharge Pressure and Low
Suction Pressure
1. See “High Discharge Pressure” and “Low
Suction Pressure”.
High Discharge Pressure or Low Suction
Pressure
1. See “High Discharge Pressure” and “Low
Suction Pressure”.
Improper Thermostat Setting
1. Readjust the setting.
Insufficient Cooling
Defective Unload Mechanism
1. Adjust unload mechanism. Repair or
replace unloaded parts, if necessary.
Slugging Due to Liquid Flooding Back to
Compressor
1. Check the superheat of suction gas. Keep
the superheat in proper range.
Noisy Compressor
Worn parts
1. Check for the sound of internal parts.
Replace the compressor, if necessary.
Miscellaneous Noise
Loose Fixed Screw
1. Tighten the screws of all parts.
Trouble with the Thermistor
1. Adjust the setting temperature.
2. Replace the thermistor.
Trouble with the Solenoid Valve
1. Check the coil in the solenoid valve.
2. Check oil passage for clogging.
Unloaded Does not Function
Worn Unloader Mechanism
1. Check the unloaded system parts in the
compressor.
High Condenser Air Temperature or
Insufficient Air Flow Through the Condenser
1. Check the fan operation.
2. Check for coil clogging; clean, if
necessary.
Defective Check Valve or partially Closed
Liquid Line Valve
1. Check the valves, capillary tubes and
strainer. Replace, if necessary.
Overcharged Refrigerant
1. Purge the refrigerant.
Air or Non-Condensable Gas in the Refrigerant
Cycle.
1. Purge the gas from the refrigerant cycle.
High Discharge Pressure
Suction Pressure is Higher than Standard
1. See “High Suction Pressure”.
Extremely Cold Condenser Air
1. Check the ambient Temperature.
Insufficient Refrigerant Charge
1. Add Refrigerant.
Leakage from the Compressor Discharge
Valve
1. Replace the valves. Replace the
compressor, if required.
Low Discharge Pressure
Suction Pressure is Lower than Standard
1. See “ Low Suction Pressure”
High Inlet Temperature of Chilled Water
1. Check the insulation of the piping.
2. Check the installation specifications.
High Suction Pressure
Excessive Opening of Expansion Valve
1. Readjust the opening, or replace, if
defective.
Low Inlet Temperature of Chilled Water
1. Check the installation specifications.
Improperly Adjusted Expansion Valve or Faulty
Valve
1. Adjust for correct superheat. Repair or
replace, if necessary.
Insufficient Refrigerant Charge
1. Add Refrigerant.
Excessive Oil in the Water Cooler
1. Purge Oil.
Low Suction Pressure
Scales on Water Cooler Plates
1. Clean the plates.
