Toshiba HWS-803XWHM3-E Service Manual page 98

[A08] Error Low pressure sensor lowering operation failure (Cooling/Defrosting
operation)
Start
Flow switch is normal
Yes
Excess air
noise comes from
inside pump
No
Chattering
noise comes from
flow switch
No
Continued
operation at low outside
temperature and at 15°C or lower
set temperature
No
Defrosting
takes 15 mins or longer
(Frost remains)
No
Lo pressure sensor
is normal
Yes
Replace water heat
exchange control board
No
Yes Secure water
circulation amount
Yes
Circulation flow
shortage
Yes
(Cooling overload operation)
Yes
No
Remove sufficiently
excess air
Waste stuck inside
water circuit
12 M or longer water
pipe to a branch,
or 5 or less branches
97
Replace flow switch
Remove waste
Place buffer tank and
the second pump
Raise set temperature
Defrost outdoor unit
where frost remains
Replace lo pressure sensor