Airwell VVFA Series Service Manual page 55

[40] High pressure too high failure
If characteristic
of high pressure
sensors are normal
Yes
If stop valve
opens fully
Yes
If in cooling
outdoor fan motor
runs normally
Yes
If in heating indoor fan
motor runs normally
and if filter is clogged
No
Check if piping
system is clogged
No
Replace pressure sensor
No
Open stop valve
No
Check fan motor
Yes
Check indoor
Yes
Clear the piping
53