Hitachi UTOPIA RAS-4HVRP2E - Page 278

10 Troubleshooting
Troubleshooting procedure
SMGB0136 rev.0 - 07/2021
276
Alarm code
21
Abnormality of High Pressure Sensor
• 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 output voltage of the high pressure sensor decreases to 0.1V or less, or increases to
4.9V or more during operation.
Phenomenon
Cause
Check Item
Action (Turn OFF
Main Switch)
No
No
No
Yes
Yes
Yes
Is there incorrect connection of
connector CN100 on Outdoor
Unit PCB?
Is 5V applied between #1 and #3
of connector CN100 on Outdoor
Unit PCB?
Is voltage between #2 and #3
of connector CN100 on Outdoor
Unit PCB 0.1V or less, or 4.9V
or more?
Failure of High Pressure Sensor
Failure of Outdoor Unit PCB
Failure of Outdoor Unit PCB
Connect CN100 correctly
Failure of Outdoor Unit PCB
Replace Outdoor Unit PCB and
check operation
Replace Outdoor Unit PCB if
faulty
Replace High Pressure Sensor
Malfunction of High Pressure Sensor
due to Clogging Piping
Indication Value of
High Pressure (Pd) is
Excessively High or Low