Hitachi SAMURAI Series Service Manual page 132

4 Troubleshooting
Analysis and countermeasure of abnormalities
Phenomenon
Activation
of high
pressure
switch
due to
excessively
high
discharge
pressure
Discharge
gas over-
increase is
activated
Chiller unit
stops during
heating
operation
Activation of
overcurrent
protection
control for
compressor
Activation of
compressor
internal
thermo
Activation of
overcurrent
relay for
pump
124 SMGB0120 rev.0 - 11/2017
Cause
Mixture of non-condensable gas in
refrigerant cycle
Clogging of pipes at discharge side
Clogging of expansion valve
Clogging of check valve
Clogging of strainer
Formation of lime deposit inside
heat exchanger
High temperature of the hot water
inlet at the heat exchanger
Suction gas temperature is too
high (excessive super heat)
Failure of thermistor for control of
discharge gas
Excessive compressor operating
current
Single phase operation
Faulty compressor bearing
Insulation failure of compressor
motor
Pump locked
Inappropriate RC value of
overcurrent relay for pump
Faulty overcurrent relay for pump
Check Item Action · Countermeasure
Stop the chiller unit
and check the relation
between water
temperature and
pressure
Check for clogging
Remove clogging, or replace
Check difference of
temperature before and Replace or wash the strainer
after the strainer
Check for dirt inside heat
exchanger
Check whether the usage
range is being exceeded
Gas leakage or
insufficient refrigerant
Malfunction of check
valve
Clogging of expansion
valve
Malfunction of the
expansion valve
Check connection with Replace thermistor for control
a tester
Power supply voltage too Set voltage during operation to
high or too low
Measure voltage between each
Phase unbalance in
power supply voltage
Discharge pressure too Investigation to determine the
high
Power source fuse blown
Loosening of terminal-
type screws of power
source
Rough contact of
electromagnetic contactor
of compressor motor
It becomes locked
Measure insulation
resistance
Check frozen water,
clogging by foreign
bodies, etc.
Check RC value and
pump operating current
Press reset button.
Replace electromagnetic switch
Check running current
Recharge refrigerant after
vacuum pumping
Remove clogging
check valve
Clean heat exchanger
This is not a failure
Charge correct refrigerant
volume after checking gas
leakage
Replace check valve
Remove clogging
Replace expansion valve
of discharge gas
rated voltage
phase, and consult with the
power company
cause
Replace power source fuse
Retighten screws
Replace contact
Compressor replacement
Remove
Change RC value or replace
electromagnetic switch