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