Hitachi RWM-(H)FSN3E, Service Manual

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12 Troubleshooting
SMGB0070 rev. 1 - 08/2011
394
Alarm code
76
Freeze Protection Stop by indoor liquid temperature thermistor
• 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 refrigerant temperature of the indoor unit is lower than -20ºC for 30 seconds.
No
Is the water
refrigerant tempe-
rature (THML and THMg)
measured correctly?
Faulty PCB1 or PCB2 (Check PCBs)
Are the
connectors between
PCB1 and PCB2 connected
correctly?
PCB1
CN9-CN1
CN5-CN2
CN6-CN3
CN2-CN4
PCB2
Are thermistors
THMg & THMl
correct? (Refer to Alarms
13/14 procedures )
Yes
Yes
Yes
1
Wiring check, repair breaking of wire, wrong wiring
Check THMg or THMI and replace it
No
No
Contact your local dealer
2
3
4
5
6
7
8
9
10
Refer to Alarm 70 procedures
Check that the refrigerant thermistors
(THML & THMg) are positioned correctly
Check to make sure the unit is operating within
operating range (refer to Operating range chapter)
Check for shortage of refrigerant gas leakage
Clogging of plate heat exchanger
Clogging of expansion valve and strainer
Check valve malfunction
Expansion valve malfunction
Make sure that the water volume of the installation
is above minimum required for the unit
(Refer to
Installation water charge
chapter)
Contact your local dealer