Troubleshooting Si-95
102 Troubleshooting Inverter K Series
2.26 Low Pressure Drop Due to Refrigerant Shortage or Electronic Expansion
Valve Failure
Remote Controller
Display
UU
UU
00
00
Supposed Causes ■ Refrigerant shortage or refrigerant system clogging (incorrect piping)
■ Defect of pressure sensor
■ Defect of outdoor unit PC board
Troubleshooting
(VF052)
The suction
pipe temperature minus
coil temperature is 20 ˚C
or higher.
Resistance
is normal when
measured with the
suction pipe thermistor
(R4-1T, R4-2T) and coil
thermistor (R2-1T, R2-2T)
disconnected from
the outdoor
unit PC
board.
Out of gas or refrigerant system is
clogged. Requires check of
refrigerant system.
Replace the thermistor.
Replace the outdoor unit PC
board.
YES
NO
NO
Out of gas or refrigerant system is
clogged. Requires check of
refrigerant system.
Replace outdoor unit PC board.
YES
YES
NO
Cooling
Low pressure
is 1.0 kg/cm² (0.098 MPa) or
less.
The voltage
of X21A pins (2)
and (3) on both sides of
outdoor unit PC board (A1P) is
0.8 VDC or less.
(Pressure sensor
output
voltage)
NO
NO
YES
YES
Replace pressure sensor.
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