Airwell VVFA Series Service Manual page 54

[39-0, 39-1] Low pressure too low and compression ratio too high
measured data by sensor
[39-2] Compression ratio too low
If actual pressure is in
conformance with the
Yes
Check if stop valve
is open fully
Yes
Check if system is
lack of refrigerant
No
Check if terminal of
electronic expansion
valve coil is fixed well
Yes
Check if piping
system is clogged
If actual pressure is in
conformance with the
measured data by sensor
Yes
Check if compressor
running current is normal
Yes
Check if 4-way valve
is interconnected
No
Replace pressure sensor
No
Open stop valve
Yes
Recharge refrigerant
No
Re-connect the terminals
Yes
No
Replace pressure sensor
No
Check compressor
Yes
Replace 4-way valve
52
Clear the piping