Hitachi UTOPIA RAS-4HVRP2E Service Manual page 274

10 Troubleshooting
Troubleshooting procedure
13
Alarm code
• The alarm code is flashed on the 7-segment display of the outdoor unit.
• The alarm code is displayed on the wired controller of the indoor unit.
This alarm code is displayed when a short circuit (0.24kΩ or less) or disconnection (840kΩ or more) of the thermistor is
detected during a heating or cooling operation. The operation automatically restarts when the malfunction is removed.
Phenomenon
Failure of Freeze
Protection Thermistor
Failure of Indoor Unit PCB
272 SMGB0136 rev.0 - 07/2021
Abnormality of Thermistor for Liquid Refrigerant Pipe Temperature at Indoor Unit Heat Exchanger
(Freeze Protection Thermistor)
Is thermistor THM3 (for freeze
protection) connected to
THM3 of indoor Unit PCB?
Yes
Is resistance of THM3
between 0.24kΩ and 840kΩ?
Yes
Failure of Indoor Unit PCB
Cause
Failure
Incorrect Connection
No
Connect them
No
Failure of Thermistor
Refer to "Alarm Code 11"
for thermistor resistance
Check Item
Check resistance
Check wiring to Indoor Unit PCB
Replace Indoor Unit PCB and
check operation
Action (Turn OFF
Main Switch)
Replace thermistor if faulty
Correctly connect wires
Replace Indoor Unit PCB if
faulty