Hitachi FS3 Series, Service Manual

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50
TROUBLESHOOTING
Alarm Code
43
Activation to Protect System from Low Compression Ratio
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?
No
Check the inverter.
Yes
Does the compressor operate?
No
Check the compressor and power
cable.
Yes
Is the four-way valve spindle mounted
at middle position?
Yes
Replace the four-way valve if faulty
No
Are the high-pressure sensor and the
low-pressure sensor good?
No
Replace the high-pressure sensor
or the low-pressure sensor if faulty.
Yes
Is there a leak in the
Solenoid Valve for Hot Gas Bypass
(SVA)?.
Yes
Replace the Solenoid Valve (SVA)
if faulty.
No
Check if the intake air temperature is
too low at the indoor or outdoor units.
Phenomenon Cause Check Item
Action
(Turn OFF main switch)
Inverter is not Functioning Check inverter. Repair faulty part.
Compressor is not Operating Check compressor. Replace comp. if faulty.
Valve Stoppage at Medium
Position of 4-Way Valve
Measure suction pipe
temp. of 4-way valve. Replace 4-way valve if
faulty.
Abnormality of High or Low
Pressure Sensor
Check connector for PCB,
power source and pressure
indication.
Replace sensor if faulty.
Excessively Low Indoor
Intake Air Temperature
Check indoor unit and outdoor
unit air temp. thermistor.
Replace thermistor if
faulty.
Excessively
Low
Compression
Ratio
Leakage from Solenoid
Valve: SVA Outdoor Unit
Check Solenoid Valve. Replace SVA if leaking.