Hitachi SAMURAI Series Service Manual page 131

4. Troubleshooting
Analysis and countermeasure of abnormalities
Phenomenon
Load bigger than cooling capacity.
Suction
pressure is
too low.
(Low
pressure
interruption
The
control
machine is
activated)
working, but
the cooling
effect is
poor
Discharge
pressure
too high
(High
pressure
switch
activation)
Malfunction of check valve
Sounds
come from
The
the com-
machine is
pressor
working, but
it produces
abnormal
noises
Howling from the electrical contactor
Vibration of cabinet
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SMGB0097 rev.0 - 07/2015
Cause
Gas leakage or insufficient
amount of refrigerant
Clogging of expansion valve
Malfunction of the expansion
valve
Clogging of suction pipes
Malfunction of check valve
Insufficient volume of water
Pump inverse rotation
Formation of lime deposit
inside heat exchanger
Refrigerant overcharge
Mixture of non-condensable
gas in refrigerant cycle
Clogging of pipes at discharge
side
Clogging of expansion valve
Malfunction of expansion
valve
Faulty compressor
Incorrect installation or
loosening of various
tightening bolts
Liquid compression
Oil hammer
Oil heater is not being
supplied power during stop
Exhaustion and damage
inside the compressor
Check Item
Calculate heat load.
Check super heat
Check for clogging
Check operation of expansion
valve
Check whether there is temp
difference in the pipes
There is temperature difference
at the check valve
Check cold water inlet/outlet
temperature difference
Check rotational direction
Check for dirt at the heat
exchanger
Check cycle temperature
Stop the chiller unit and check
the relation between water
temperature and pressure
Check for clogging
Check for clogging
Check operation of expansion
valve
Check temperature difference
before and after check valve
Check pressure, cycle
temperature and current
Inspection of loosening of each
tightening bolt
Check temperature and pressure
of suction gas
Check temperature and amount of
oil in suction gas
Check the power supply to the oil
heater
Abnormal noises produced inside
the compressor
Check for rough contact
Check for loosening of screws
Action · Countermeasure
Set the machine to a larger
capacity
Charge correct refrigerant volume
after checking gas leakage
Remove clogging
Replace expansion valve
Remove clogging
Replace check valve
Increase volume of water
Fix to correct direction
Clean heat exchanger
Charge correct volume
Recharge refrigerant after vacuum
pumping
Remove clogging.
Replace expansion valve
Replace check valve
Compressor replacement
Tighten bolts even more
Secure super heat
Check or replace compressor
Replace oil heater
Compressor replacement
Replace contact
Retighten screws