Hitachi FSG Series Service Manual page 29

Phenomenon
Insufficient Air Flow to Heat
Exchanger (Outdoor Heat
Exchanger during Cooling
Operation or Indoor Heat
Exchanger during Heating
Expansion Valve Trouble
Activation of
High Pressure
Switch due to
Excessively
High Discharge
Pressure
Excessively High Temp.
Faulty High
Pressure
Cause
Operation)
Air to Indoor Unit Heat
Exchanger
Faulty
Pressure
Switch
Insufficient
Contacting
Switch
Incorrect
Connection
TROUBLESHOOTING
Check Item
Clogging of Heat
Exchanger?
Check for dust on air filter
Check for any obstacles at
inlet or outlet of outlet of
heat exchanger.
Check the service space.
Check for speed.
(Outdoor Fan: Cooling /
Indoor Fan: Heating)
Disconnected of
Connector
Fully opened and locked.
(see page 1-93)
Calculate heat load.
Check for hot air near the
ceiling (Heating).
Check for short circuited
air (Heating).
Check for other heat
source.
Measure discharge pressure.
Check continuity after
decreasing of pressure.
Measure resistance by
tester.
Check connections.
1
21
Action
(Turn OFF main switch)
Remove clogging.
Remove dust.
Remove obstacles.
Secure service space.
Replace fan motor if faulty.
Repair looseness or
reconnect connector.
Replace expansion valve.
Reduce heat load or use a
bigger unit.
Make good circulation.
Remove short-circuited
air.
Remove heat source.
Replace it if faulty.
Repair looseness.
Replace connector.
Repair connections.