Hitachi FSG Series Service Manual page 24

1
TROUBLESHOOTING
16
1.1.7 ABNORMALITIES OF DEVICES (Cont.)
Phenomenon
Excessively
Insufficient
Heating
Operation
Malfunction of Check Valve of
Excessively
High Suction
*1): Refer to Item 16.6 of TC
Cause
Insufficient
Air Flow to
Indoor Unit
Heat
Exchanger
Excessively
High Air
Temp. to
High
Indoor Unit
Discharge
Heat
Pressure
Exchanger
Excessively
Charged
Refrigerant
Non-
Condensate
Gas in Ref.
Cycle
Clogging of
Discharge
Pr. Piping
Malfunction or Internal
Leakage of 4-Way Valve
Outdoor Unit
Failure of
Bypass
Solenoid
Valve
Pressure Malfunction
or Internal
Leakage of
4-Way Valve
Discharge Temp. of Indoor
Unit Is Unstable.
Check Item
Check for filter clogging.
Check for any obstacles at
inlet or outlet of indoor
unit.
Check indoor fan speed.
Check whether or not
short-circuited air exists.
Check refrigerant quantity
*1).
Check refrigerant quantity
*1).
Check for clogging
Check temp. difference at
inlet and outlet of 4-way
valve.
Check temp. difference at
inlet and outlet of check
valve.
Chek for leakage of
selenoid valve
Check temp. difference at
inlet and outlet of 4-way
valve.
Check for expansion valve
of indoor unit in the same
system.
Action
(Turn OFF main switch)
Remove clogging.
Remove Obstacles.
Replace fan motor.
Remove cause of short
circuited air.
Correctly charge
refrigerant
Recharge refrigerant after
vacuum pumping
Remove clogging
Replace 4-way valve.
Replace check valve.
Replace solenoid valve.
Replace 4-way valve
Replace failed expansion
valve of indoor unit.