Hitachi FSG Series Service Manual page 52

1
TROUBLESHOOTING
44
Alarm Code
29
n "RUN" light flickers and "ALARM" is indicated on the remote control switch.
n The unit No., alarm code and the unit code is alternately indicated on the set temperature section, and the
unit No. and alarm code are indicated on the display of the outdoor unit PCB.
‘
This alarm code is indicated when the pressure sensor voltage decreases lower than 0.1 V or increases
higher than 4.9V during running.
Is the connection CN8 of
the outdoor unit PCB1
mated loose?
No
Is 5 VDC applied across #1
and #3 of the connector
CN8 of the outdoor circuit
board PCB1?
Yes
Is voltage under 0.1 VDC
or over 4.9 VDC across #2
and #3 of the connector
CN8 of the outdoor unit
PCB1?
Yes
Is the Check Joint clogged?
No
Abnormality with low
Pressure Sensor.
Phenomenon
Faulty High
Pressure
Sensor
Faulty PCB
Indicated
Pressure Value is
Sensor due to Faulty Check
Excessively High
or Low
Abnormality of Low Pressure Sensor for Outdoor Unit
Yes
No
No
Yes
Cause
Fault
Incorrect Connection
Malfunction of Pressure
Joint
Check Item
Check output voltage is
correct.
Check connections.
Replace PCB and check
operation.
Check for clogging of
check joint.
Connect correctly.
Faulty PCB1
Faulty PCB1
Replace check joint.
Action
(Turn OFF main switch)
Replace pressure sensor if
faulty.
Repair wiring and
connections.
Replace PCB if faulty.
Replace check joint.