Hitachi RAS-H(V)RNME-AF Service Manual page 368

12 Troubleshooting
18
Alarm code
• The alarm code is displayed on the LCD User interface.
• The alarm code is displayed on the seven segments of the indoor unit PCB.
• This alarm code is displayed when the thermistor is short-circuited (less than 0.24 kΩ) or cut (greater than 18.2 kΩ)
when boiler enabled.
Is THMwo3
connected to (intake)
terminals 29 & 29 of TB2?
Yes
Are the wires
between terminal
board 2 and PCB2
connected correctly?
CN15-1-TB2-28
PCB2
CN15-3-TB2-29
Is resistance
of THMwo3 between
0.24kΩ and 18.2kΩ?
Yes
Are the
connectors between
PCB1 and PCB2 connected
correctly?
CN9-CN1
CN5-CN2
PCB1
CN6-CN3
CN2-CN4
Yes
Is the
temperature of
THMwo3 between 100ºC
and -80ºC?
Yes
Faulty PCB1 or PCB2
(Check PCBs)
358
SMGB0070 rev. 1 - 08/2011
Water outlet 3 (boiler circ.) Temperature (Two3) Thermistor Abnormality
No
No
TB2
No
No
PCB2
No
Thermistor characteristics
Wiring check, repair
breaking of wire, wrong
Wiring check, repair
breaking of wire, wrong
Check correct position of
THMwo3 and correct it
Temperature (ºC)
Connect it
wiring
Faulty thermistor
(Change it)
wiring