Hitachi SAMURAI Series Service Manual page 129

4. Troubleshooting
Analysis and countermeasure of abnormalities
Phenomenon
Pump is
Faulty PCB
operating, but
compressor is
not operating.
Failure of remote control switch
Faulty PCB
Faulty elec-
tromagnetic
Pump.
contactor of
Compressor
compressor
is not
operating
Activation of
high pressure
switch due
to exces-
Chiller Unit
sively high
stops during
Cooling discharge
operation
pressure
Thermostat
for discharge
gas overheat
prevention is
activated
122
SMGB0097 rev.0 - 07/2015
Cause
Bad connection of wiring
Faulty PCB
Bad connection of wiring
Faulty PCB
Defective thermistor
Disconnection of coil
Bad connection of contact
Thermostat is operating
Faulty compressor motor
Faulty compressor
Low voltage at startup.
Refrigerant overcharge
Mixture of non-condensable
gas in refrigerant cycle
Clogging of discharge pipes
Clogging of expansion valve
Clogging of check valve
Clogging of strainer
High temperature of the cold
(hot) water inlet at the heat
exchanger
Suction gas temperature is
too high.
(Excessive super heat)
Check Item
Check connection with a tester
Check connection with a tester
Check PCB with self-diagnosis
Operation is possible by activation
from the main unit side
Check connection with a tester
Measure resistance of thermistor
Check connection with a tester
Voltage measurement between
contacts of electromagnetic
contactor
Try to turn the knob of the
thermostat, in order to change the
temperature.
Measure resistance between wires
Howling sounds originating from
compressor
Voltage measurement
Check cycle temperature
Stop the chiller unit and check the
relation between water temperature
and pressure
Check for clogging
Check difference of temperature
before and after the strainer
Check whether the usage range is
being exceeded
Gas leakage or insufficient
refrigerant
Malfunction of the expansion valve
Action · Countermeasure
Correct wiring connection
Replace PCB
Replace remote control
switch
Correct wiring connection
Replace thermistor
Replace electromagnetic
contactor
This is not a failure.
Compressor replacement
Consult with the power
company
Charge correct volume
Recharge refrigerant
after vacuum pumping
Check for clogging
Remove clogging, or
replace check valve
Replace or wash the
strainer
Investigate the situation
of heat load well and
take action
Charge correct
refrigerant volume after
checking gas leakage
Replace expansion valve