Hitachi FSXN Series Service Manual page 170

8 Troubleshooting
Phenomenon
Excessively
High
Discharge
Pressure
Insufficient
Cooling
Operation
Malfunction or Internal
Leakage of Reversing Valve
Excessively
Low Suction
Pressure
Discharge Temp. of
Indoor Unit is Unstable.
164
SMGB0065 rev. 1 - 12/2010
Cause
Check Clogging of
Outdoor Unit
Heat Exchanger.
Obstacles at inlet or
Insufficient
outlet of outdoor unit
Air Flow to
heat exchanger?
Outdoor Unit
Heat
Is service space for
Exchanger
outdoor unit sufficient?
Correct Fan Speed?
Excessively
Short-Circuited Air
High Air
to Outdoor Unit?
Temp. to
Outdoor Unit
Any Other Heat Load
Heat
near Outdoor Unit?
Exchanger
Excessively
Check expansion valve
Charged
opening.
Refrigerant
Non-
Check each temp.
Condensed
and pressure.
Gas in Cycle
Clogging of
Discharge Check for clogging.
Piping
Check for clogging.
Check for connecting
cord and connector.
Failure or
Malfunction Is there operation
of Expansion sound from coil?
Valve
Is thermistor on
compressor normal?
Is thermistor installed
correctly on
compressor?
Check temp. difference
at inlet and outlet of
reversing valve.
Failure of
Bypass Check for leakage of
Solenoid solenoid valve.
Valve
Malfunction
or Internal Check temp. difference
Leakage of between inlet and
Reversing outlet of reversing valve.
Valve
Check for expansion
valve of indoor unit in
the same system.
Check Item
(Turn OFF Main Switch)
Remove clogging.
Remove obstacles.
Secure service space.
Replace fan motor.
Remove cause of
short-circuited air.
Remove heat source.
Correctly charge
refrigerant.
Charge refrigerant
after vacuum pumping.
Remove clogging.
Remove clogging.
Replace connector.
Replace thermistor.
Correctly install it.
Replace reversing valve.
Replace solenoid valve.
Replace reversing valve.
Replace failed
expansion valve of
indoor unit.
Action
Replace coil.