Hitachi UTOPIA RAS-4HVRP2E Service Manual page 286

10 Troubleshooting
Troubleshooting procedure
44
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.
If the pressure (Ps) of the compressor is more than 1.4 MPa for a minute, the compressor stops. The operation
automatically restarts after three minutes. If this occurs again twice in the next 30 minutes, this alarm code is displayed.
Is the refrigerant leakage from solenoid
valve (SVA)?
No
Is 4-Way valve stopped at middle
position?
No
Is low pressure sensor normal?
Yes
Check that indoor/outdoor inlet air temperature
is not too high
Phenomenon
Excessively Increasing
Low Pressure
284 SMGB0136 rev.0 - 07/2021
Activation of Low Pressure Increase Protection
Yes
Yes
No
Cause
Leakage from Solenoid Valve (SVA)
Valve Stoppage at Middle Position of
4-Way Valve
Abnormal Suction Pressure Sensor
Excessively High Indoor Unit and
Outdoor Unit Inlet Air Temperature
O.U. PCB: Outdoor Unit PCB
Replace solenoid valve (SVA) if faulty
Replace 4-way valve if faulty
Replace low pressure sensor if faulty
Check Item
Check outlet pipe temp. of
solenoid valve (SVA)
Measure suction gas pipe
temp. of 4-way valve
Check connectors of Outdoor
Unit and power supply
Check indoor unit and outdoor
unit inlet air temp. thermistor
Action (Turn OFF
Main Switch)
Check connecting wires.
Replace solenoid valve (SVA)
if faulty.
Replace 4-Way valve if faulty
Replace sensor if faulty
Replace thermistor if faulty