Hitachi UTOPIA RAS-4HVRP2E - Page 288

10 Troubleshooting
Troubleshooting procedure
SMGB0136 rev.0 - 07/2021
286
Alarm code
47
Activation of Low Pressure Decrease 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 low pressure (Ps) of the compressor is less than 0.09 MPa for 12 minutes, the compressor stops. The operation
automatically restarts after three minutes. If this occurs again twice in the next 60 minutes, this alarm code is displayed.
O.U: outdoor unit; I.U. PCB: indoor unit PCB
No
Yes
Is amount of refrigerant correct?
Is outdoor stop valve open?
Yes
No
Is refrigerant leaking?
No
Yes
No
Yes
Yes
No
Is low pressure sensor normal?
Are electronic expansion valves for
O.U./I.U. fully closed and locked?
Check communication cable and refrigerant piping
between indoor and outdoor units are correctly
connected
Correctly charge refrigerant
Open the stop valve
Repair leaks
Replace low pressure sensor if faulty
Check connection of connectors O.U./
I.U. PCB and electronic expansion valves.
Replace them if faulty.
? NOTE
Check the refrigerant system number setting of O.U. and I.U. PCB.
Phenomenon
Cause
Check Item
Action (Turn OFF
Main Switch)
Excessively
Decreasing Low
Pressure
Shortage of Refrigerant
Closed Stop Valve
Abnormal High Pressure Sensor
Incorrect Connection between
Indoor Unit and Outdoor Unit
Locked Electronic Expansion Valve
for O.U./I.U. (Fully Closed)
Electronic Expansion Valve Closed
by Disconnecting Td Thermistor
Faulty Outdoor Fan Motor
Faulty internal
Thermostat
Failure
Contact
Failure
Incorrect
Connection
Internal Thermostat
for Outdoor Fan is
Activated in Heating
Operation
Check charged refrigerant
volume or check for leakage
Repair leakage and correctly
charge refrigerant
Check stop valve
Open stop valve
Check connector for
O.U. PCB
Replace pressure sensor if
faulty
Check electrical system and
refrigerant system
Correctly connect indoor unit
and outdoor unit
Check connector for O.U./
I.U. PCB
Repair connector for O.U./
I.U. PCB or expansion valve.
Replace if faulty.
Electronic Expansion Valve
Closed by Disconnecting Td
Thermistor
Repair or replace Td
Thermistor
Measure coil resistance and
insulation resistance
Replace outdoor fan motor
Check for continuity after
temperature of outdoor fan
motor decreases
Replace outdoor fan motor
Measure resistance with a
tester
Tighten or replace connector
Check connection Connect it correctly