4. Troubleshooting
Analysis and countermeasure of abnormalities
SMGB0082 rev.1 - 07/2015
158
Phenomenon
Cause
Check Item
Action · Countermeasure
The
machine is
working, but
the heating
effect is
poor.
Load bigger than heating capacity.
Conduct heating load calculation
Set the machine to a larger
capacity
Suction
pressure is
too low.
(Low
pressure
interruption
control
activated)
Gas leakage or insufficient
amount of refrigerant
Check super heat
Charge correct refrigerant
volume after checking gas
leakage
Clogging of expansion valve
Check for clogging
Remove clogging
Malfunction of expansion
valve
Check operation of expansion
valve
Replace expansion valve
Clogging of suction pipes
Check whether there is
temperature difference in the pipes
Remove clogging.
Suction
pressure is
too low.
(Low
pressure
interruption
control
activated)
Malfunction of check valve
There is temperature difference
before and after check valve.
Replace check valve
Insufficient airflow to air-
side heat exchanger
Excessive adherence of dust at the
air-side heat exchanger
Remove.
Air-side heat exchanger inlet or
outlet blocked.
Insufficient service space for the
chiller unit
Secure service space
Inverse rotation of the fan motor
Change wiring of fan motor
Excessively low
temperature of the air
passing through the air-side
heat exchanger
Chiller unit is air short-circuited
Remove short-circuit.
Defrosting is not completely
conducted.
Check thermistor for defrosting
Replace thermistor for defrosting
Check 4-way valve
Replace 4-way valve
Discharge
pressure
too high.
(High
pressure
switch
activation)
Insufficient volume of water
Check cold water inlet/outlet
temperature difference
Increase volume of water
Pump inverse rotation
Check rotational direction
Fix to correct direction
Air mixture
Try to open ventilator valve
Ventilator
Hot water temperature too
high
Check activation of the hot water
thermostat
Replace thermostat
Refrigerant overcharge
Check cycle temperature
Charge correct volume
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
Check for clogging
Malfunction of expansion
valve
Check operation of expansion
valve
Replace expansion valve
Formation of lime deposit
inside water-side heat
exchanger
Check for dirt inside water-side
heat exchanger
Clean water-side heat exchanger
Wrong activation of the 4-way valve or
internal leakage
Check temperature difference of
the piping before and after 4-way
valve
Replace 4-way valve
Disconnection of 4-way valve coil
Check connection with a tester
Replace 4-way valve coil
Malfunction of check valve
Check temperature difference
before and after check valve
Replace check valve
