Hitachi SAMURAI Series Service Manual page 130

4 Troubleshooting
Analysis and countermeasure of abnormalities
Phenomenon
Faulty PCB
Pump is
operating, but
compressor is
not operating.
Faulty PCB
Faulty
electromagnetic
Pump.
contactor of
Compressor is
compressor
not operating
Activation of
high pressure
switch due to
Chiller Unit
excessively
stops during
high discharge
Cooling
pressure
operation
Thermostat
for discharge
gas overheat
prevention is
activated
122 SMGB0120 rev.0 - 11/2017
Cause
Bad connection of wiring
Faulty PCB
Failure of remote control switch
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