Hitachi UTOPIA RAS-4HVRP2E - Page 279

10 Troubleshooting
Troubleshooting procedure
SMGB0136 rev.0 - 07/2021
277
10
Alarm code
22
Abnormality of Outdoor Air Thermistor (Outdoor Unit Ambient Thermistor)
• Thealarmcodeisashed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(0.2kΩorless)ordisconnection(500kΩormore)ofthethermistoris
detected during heating or cooling operation.
Is thermistor THM7
connected to THM7 of
Outdoor Unit PCB?
Is resistance of THM7
between0.2kΩand500kΩ?
Connect them
Failure of Thermistor
Failure of O.U. PCB
Phenomenon
Cause
Check Item
Action (Turn OFF
Main Switch)
Failure of Thermistor
for Outdoor Air Temp.
Failure
Incorrect Connection
Check resistance
Check wiring to Outdoor Unit
PCB
Replace thermistor if faulty
Repair wiring and connection
Replace Outdoor Unit PCB if
faulty
Replace Outdoor Unit PCB and
check operation
Failure of Outdoor Unit PCB
Thermistor
Resistance
R
T
[kΩ]
Temperature T (°C)
Thermistor Characteristics
No
No
Yes
Yes