Hitachi SAMURAI Series Service Manual page 171

4. Troubleshooting
Procedures for trouble
The following table shows efficient checking procedures for trouble.
Fault
Excessively Low Chilled water Outlet Temperature
Compressor Stops
Defective Thermistor
on Freeze Protection
Control.
Shortage of Chilled Water Flow
Air in water Circuit
High or low voltage, single-phase or phase imbalance
Compressor Stops on
Excessive Superheat
Internal Thermostat
or Discharge Gas
Defective Element
Temperature Control.
Excessive High Discharge Pressure and Low Suction
Pressure
High Discharge Pressure or Low Suction Pressure
Insufficient Cooling Improper Thermostat Setting
Defective Unload Mechanism
Slugging Due to Liquid Flooding Back to Compressor
Noisy Compressor
Worn parts
Miscellaneous Noise Loose Fixed Screw
Trouble with the Thermistor
Unloaded Does not
Trouble with the Solenoid Valve
Function
Worn Unloader Mechanism
High Condenser Air Temperature or Insufficient Air
Flow Through the Condenser
Defective Check Valve or partially Closed Liquid Line
High Discharge
Valve
Pressure
Overcharged Refrigerant
Air or Non-Condensable Gas in the Refrigerant Cycle.
Suction Pressure is Higher than Standard
Extremely Cold Condenser Air
Insufficient Refrigerant Charge
Low Discharge
Pressure
Leakage from the Compressor Discharge Valve
Suction Pressure is Lower than Standard
High Inlet Temperature of Chilled Water
High Suction Pressure
Excessive Opening of Expansion Valve
Low Inlet Temperature of Chilled Water
Improperly controlled Expansion Valve or Faulty Valve
Low Suction Pressure
Insufficient Refrigerant Charge
Excessive Oil in the Water Cooler
Scales on Water Cooler Plates
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SMGB0082 rev.1 - 07/2015
Possible Cause Check/Corrective Action
Check for excessively low setting of the chilled
water setting knob.
Check for malfunction of the thermistor. Replace, if
necessary.
Check the rotation of the pump.
Purge air.
Check the power supply line and contactor. Repair,
if necessary.
Check for refrigerant leakage.
Check the contact of the internal thermostat during
the cold condition.
See High Discharge Pressure and
Pressure.
See High Discharge Pressure and
Pressure.
Readjust the setting.
Adjust unload mechanism.
Repair or replace unloaded parts, if necessary.
Check the superheat of suction gas. Check the
position of Expansion Valve coil. Repair or replace
if necessary.
Check for the sound of internal parts. Replace the
compressor, if necessary.
Tighten the screws of all parts.
1. Adjust the setting temperature.
2. Replace the thermistor.
1. Check the coil in the solenoid valve.
2. Check oil passage for clogging.
Check the unloaded system parts in the
compressor.
1. Check the fan operation.
2. Check for coil clogging; clean, if necessary.
Check the valves and strainer. Replace, if
necessary.
Adjust the refrigerant quantity.
Purge the gas from the refrigerant cycle.
See High Suction Pressure.
Check the ambient Temperature.
Add Refrigerant.
Replace the valves. Replace the compressor, if
required.
See Low Suction Pressure
1. Check the insulation of the piping.
2. Check the installation specifications.
Check the position of Expansion Valve coil, or
replace, if defective.
Check the installation specifications.
Check the position of Expansion Valve coil. Repair
or replace, if necessary.
Add Refrigerant.
Purge Oil.
Clean the plates.
Low Suction
Low Suction
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