Hitachi RAS-2-HVNP Service Manual page 235

8. Troubleshooting
21
Alarm code
• The RUN LED flickers and "ALARM" is displayed on the remote control switch.
• The unit number, the alarm code and the unit code are alternately displayed on the set temperature section.
The unit number and the alarm code are displayed on the display of the outdoor unit PCB.
alarm code is indicated when the pressure sensor output voltage decreases (less than 0.1V) or
This
-
increases (more than 4.9V) during the operation
Is there connection
problem of CN7
on O.U. PCB1?
No
Is 12V applied
between #1 and #3 of
the connector CN7
on O.U. PCB1?
Yes
Is voltage under
0.1V or over 4.9V
between #2 and #3 of
the connector CN7
on O.U. PCB1?
Yes
Abnormality of High
Pressure Sensor.
Phenomenon
Faulty top of compressor
thermistor
Faulty PCB1
Indication of pressure value is
excessively high or low
221
SMGB0079 rev.0 - 01/2013
Abnormality of High pressure sensor for RAS-(3-12)H(V)NP(E)
Yes
No
No
Cause
Fault
Incorrect connection
Malfunction of pressure sensor due
to clogging wiring
.
Check item
Check resistance
Check wiring to PCB1
Replace PCB1 and check
operation
Connect correctly.
Faulty O.U. PCB1
Faulty O.U. PCB1
Action
(Turn OFF Main Switch)
Replace thermistor if faulty
Repair wiring and connections
Replace PCB1 if faulty
Replace pressure sensor
8