Hitachi YUTAMPO Series Service Manual page 81

6 Troubleshooting
Indoor unit
71
Alarm code
• The alarm code is displayed on the LCD controller when the temperature of the water is higher than 86 °C.
• This alarm forces the heat pump and the heater to stop.
• The unit should be stopped to release the alarm.
Is the Check and restart
No
the thermostat
heater
working? reset switch
Yes
Disconnect CN15
Relay-AR from
the PCB
Is the
Yes
Check relay-AR
heater still
continuity
working?
No
80
Alarm code
• The alarm code is displayed on the unit controller when there is no communication between indoor unit PCB and the
unit controller for 90 seconds.
• This alarm forces all operations to stop.
• The unit should be stopped to release the alarm.
Are the connections
between PCB and
LCD controller correctly
Controller
Faulty Unit controller or PCB
73 SMGB0135 rev.0 - 06/2020
Is the
heater
working?
Yes
Is there
No
continuity to
the heater
thermostat?
Yes
Faulty realy-AR
(Change it)
Communication failure between Indoor unit and LCD controller (PC-ARFTE)
connected?
Unit
PCB
CN2-1 CN20-1
CN2-2 CN20-2
CN2-3 CN20-3
CN2-4 CN20-4
Yes
(Check it)
Tank over-temperature limit protection
No Disconnect
wires and check
heater continuity
Faulty PCB
(Change it)
No
Check wiring: repair broken / wrong wiring
Contact your local dealer
No
Is there Faulty heater
continuity? (Change it)
Yes
6