Hitachi UTOPIA RAS-4HVRP2E - Page 286

10 Troubleshooting
Troubleshooting procedure
SMGB0136 rev.0 - 07/2021
284
Alarm code
44
Activation of Low Pressure Increase Protection
• 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.
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.
O.U. PCB: Outdoor Unit PCB
Phenomenon
Cause
Check Item
Action (Turn OFF
Main Switch)
Yes
No
Yes
No
No
Yes
Is the refrigerant leakage from solenoid
valve (SVA)?
Is 4-Way valve stopped at middle
position?
Is low pressure sensor normal?
Check that indoor/outdoor inlet air temperature
is not too high
Replace solenoid valve (SVA) if faulty
Replace 4-way valve if faulty
Replace low pressure sensor if faulty
Excessively Increasing
Low Pressure
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
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
Check connecting wires.
Replace solenoid valve (SVA)
if faulty.
Replace 4-Way valve if faulty
Replace sensor if faulty
Replace thermistor if faulty