Hitachi RPI-0.8FSG1 Service Manual page 28

TROUBLESHOOTING
(1.1.7 Abnormalities of Devices)
Phenomenon
Insufficient
Cooling
Operation
1-18
Cause
Indoor Heat Load is Greater
than Cooling Capacity
Gas Leakage
or Shortage
of Refrigerant
Excessively
Small
Diameter
Tube or
Long Piping
Incorrect
Activation of
Check Valve
of Outdoor
Unit
Failure or
Malfunction
of Expansion
Valve
Excessively
Low Suction
Pressure
Clogged
Capillary
Tube in
CH Unit
Clogged
Strainer in
Indoor Unit
or CH Unit
Clogging at
Low Pressure
Piping
Clogging at
Low Pressure
Piping
Insufficient
Air Flow to
Indoor Unit
Heat
Exchanger
Excessively
Low Air
Temp. to
Indoor Unit
Heat
Exchanger
Check Item
Calculate heat load.
Measure superheat.
Measure and check
field-supplied pipes.
Check whether or not
temp. difference exists
before/after check valve.
Check for clogging.
Check for connection
cord and connector.
Is there operation
sound from coil?
Is thermistor on
compressor normal?
Is thermistor
installed correctly on
compressor?
Is there dewing after
capillary tube?
Check temp. difference
at inlet and outlet of
strainer.
Check temp. difference.
Check for clogged
air filter.
Check for obstacle at
inlet or outlet.
Insufficient revolution
of indoor unit fan motor?
Check Short-circuited
indoor unit air.
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 capillary tube
in CH Unit.
Replace strainer in
indoor unit.
Remove clogging.
Clean air filter.
Remove obstacles.
Replace fan motor.
Remove cause of
short-circuited air.