Low Pressure Drop Due To Refrigerant Shortage Or Electronic Expansion Valve Failure - Daikin R407C PLUS Service Manual

Si33-105
3.25 Low Pressure Drop Due to Refrigerant Shortage or
Electronic Expansion Valve Failure
U0
Remote
Controller
Display
!
Supposed
!
Causes
!
Troubleshooting
Troubleshooting R407C PLUS Series Heat Recovery System
Out of gas or refrigerant system clogging (incorrect piping)
Defect of pressure sensor
Defect of outdoor unit PC board
Be sure to turn off power switch before connect or disconnect connector,
Caution or parts damage may be occurred.
Cooling
NO
The suction
pipe temperature minus
coil temperature is 20 ˚C
or higher.
NO
Resistance
is normal when
measured with the suction
pipe thermistor (R6T) and
coil thermistor (R2T)
disconnected from
the outdoor unit
PC board.
YES
Low pressure
YES
is 1.0 kg/cm² (0.098 MPa) or
less.
NO
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
YES
NO
Troubleshooting
YES
Out of gas or refrigerant
system is clogged. Requires
check of refrigerant system.
YES
Replace low outdoor unit PC
board.
Replace low pressure sensor.
Out of gas or refrigerant
system is clogged. Requires
check of refrigerant system.
Replace the thermistor.
Replace the outdoor unit PC
board (A1P).
(VF052)
181