Hitachi FSG Series Service Manual page 58

1
TROUBLESHOOTING
50
Alarm Code
43
n "RUN" light flickers and "ALARM" is indicated on the remote control switch.
n The unit No., alarm code and the unit code is alternately indicated on the set temperature section, and the
unit No. and alarm code are indicated on the display of the outdoor unit PCB.
‘
This alarm code is indicated when a compression ratio , e={(Pd + 0.1) /(Ps + 0.1)} is calculated from a
discharge pressure (MPa) and suction pressure (MPa) and the condition lower than e= 1.8 occurs more
than 3 times including 3 in one hour.
Does the inverter operate?
Yes
Does the compressor operate?
Yes
Is the four-way valve spindle mounted
at middle position?
No
Are the high-pressure sensor and the
low-pressure sensor good?
Yes
Is there a leak in the
Solenoid Valve for Hot Gas Bypass
(SVA)?.
No
Check if the intake air temperature is
too low at the indoor or outdoor units.
Phenomenon
Inverter is not Functioning
Compressor is not Operating
Valve Stoppage at Medium
Excessively
Position of 4-Way Valve
Low
Compression
Abnormality of High or Low
Ratio
Excessively Low Indoor
Valve: SVA Outdoor Unit
Activation to Protect System from Low Compression Ratio
No
No
Yes
No
Yes
Cause
Pressure Sensor
Intake Air Temperature
Leakage from Solenoid
Check the compressor and power
Replace the four-way valve if faulty
Replace the high-pressure sensor
or the low-pressure sensor if faulty.
Replace the Solenoid Valve (SVA)
Check Item
Check inverter.
Check compressor.
Measure suction pipe
temp. of 4-way valve.
Check connector for PCB,
power source and pressure
indication.
Check indoor unit and outdoor
unit air temp. thermistor.
Check Solenoid Valve.
Check the inverter.
cable.
if faulty.
Action
(Turn OFF main switch)
Repair faulty part.
Replace comp. if faulty.
Replace 4-way valve if
faulty.
Replace sensor if faulty.
Replace thermistor if
faulty.
Replace SVA if leaking.