Hitachi RAS-(3-6)HVNC1(E) - Page 227

8 Troubleshooting
213
SMGB0087 rev.0 - 12/2013
8
Phenomenon Cause Check item
Action
(Turn OFF the main switch)
Insufcient cooling
process
Excessively high
discharge pressure
Insufcient air ow to
the outdoor unit heat
exchanger
Clogging of the outdoor unit
heat exchanger?
Remove the clogging
Obstacles at the inlet or the
outlet of the outdoor unit
heat exchanger
Remove the obstacles
Is the service area for the
outdoor unit sufcient?
Secure the service area
Correct fan speed? Replace the fan motor
Excessively high air
temperature to the
outdoor unit heat
exchanger
Short-circuited air to the
outdoor unit?
Remove the cause of the
short-circuited air
Any other heat load near the
outdoor unit?
Remove the heat source
Excessively charged
refrigerant
Expansion valve opening
Correctly charge the
refrigerant
Non-condensate gas
in cycle
Check each temperature and
each pressure
Charge the refrigerant after
the vacuum pumping
Clogging of the
discharge piping
Check for clogging Remove the clogging
Failure or malfunc-
tion of the expansion
valve
Check for clogging Remove the clogging
Check the connection cord
and the connector
Replace the connector
Is there an operation sound
from the coil?
Replace the coil
Is the thermistor on the
compressor normal?
Replace the thermistor
Is the thermistor installed
correctly on the compressor?
Correctly install the
thermistor
Malfunction or internal leakage of the 4-way
valve
Check the temperature
difference at the inlet and the
outlet of the 4-way valve
Replace the 4-way valve
Excessively low suc-
tion pressure
Malfunction or
internal leakage of
the 4-way valve
Check the temperature
difference between the inlet
and the outlet of 4-way valve
Replace the 4-way valve
Failure of solenoid
valve for bypass
Check refrigerant leakage of
solenoid valve
Replace solenoid valve
Discharge temperature of the indoor unit is
unstable
Check the expansion valve
of the indoor unit in the same
system
Replace the failed expansion
valve of the indoor unit