Hitachi FSXN Series Service Manual page 169

8 Troubleshooting
Phenomenon
Indoor Heat Load is Greater
than Cooling Capacity
Insufficient
Cooling
Operation
Excessively
Low Suction
Pressure
163
SMGB0065 rev. 1 - 12/2010
Cause Check Item
Calculate heat load.
Gas Leakage
or Shortage Measure superheat.
of Refrigerant
Excessively
Small
Measure and check
Diameter
field-supplied pipes.
Tube or
Long Piping
Incorrect
Activation of Check whether or not
Check Valve temp. difference exists
of Outdoor before/after check valve.
Unit
Check for clogging.
Check for connection
cord and connector.
Failure or
Malfunction Is there operation
of Electronic sound from coil?
Expansion
Valve
Is thermistor on
compressor normal?
Is thermistor
installed correctly on
compressor?
Clogged
Strainer in
Check temp. difference
Indoor Unit
at inlet and outlet of
Clogging at
strainer.
Low Pressure
Piping
Clogging at
Low Pressure Check temp. difference.
Piping
Check for clogged
Insufficient
air filter.
Air Flow to
Indoor Unit
Heat
Check for obstacle at
Exchanger
inlet or outlet.
Excessively
Insufficient revolution
Low Air
of indoor unit fan motor?
Temp. to
Indoor Unit
Check Short-circuited
Heat
indoor unit air.
Exchanger
Action
(Turn OFF Main Switch)
Use a bigger unit.
Correctly charge
refrigerant after
repairing gas leakage.
Use correct pipes.
Replace check valve
for outdoor unit.
Remove clogging.
Replace connector.
Replace coil.
Replace thermistor.
Correctly install it.
Replace strainer in
indoor unit.
Remove clogging.
Clean air filter.
Remove obstacles.
Replace fan motor.
Remove cause of
short-circuited air.
8