Hitachi mini-HNRQ1 Series Service Manual page 104

Alarm
47
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 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.
Event
Excessively
Decreasing
Low Pressure
Internal
Thermostat for
Outdoor Fan
is Activated
in Heating
Operation
Activation of Low Pressure Decrease Protection
Cause
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
Failure
Faulty
Internal
Contact
Thermostat
Failure
Incorrect
Connection
O.U: outdoor unit; I.U. PCB: indoor unit PCB
Check Item
Check charged ref.
volume or check for
leakage.
Check stop valve.
Check connector
for O.U. PCB.
Check electrical system
and ref. system.
Repair connector for O.U.
Check connector for
/I.U. PCB or expansion
O.U./I.U. PCB.
valve. Replace it if faulty.
Check Td thermistors
for compressors and
measure Td thermistor
resistance.
Measure coil resistance
and insulation resistance.
Check for continuity
after temperature of
outdoor fan motor
decreases.
Measure resistance
with a tester.
Check connection.
97
TROUBLESHOOTING
Action
(Turn OFF Main Switch)
Repair leakage and
correctly charge ref..
Open stop valve.
Replace pressure
sensor if faulty.
Correctly connect
indoor unit and
outdoor unit.
Repair or replace
Td thermistor.
Replace outdoor fan
motor if faulty.
Replace outdoor fan
motor.
Tighten or replace
connector.
Connect it correctly.