Low Pressure Drop Due To Refrigerant Shortage Or Electronic Expansion Valve Failure - Panasonic Urban Multi MX1R Series Service Manual

Troubleshooting
3.25 Low Pressure Drop Due to Refrigerant Shortage or Electronic Expansion
Valve Failure
U0
Remote Controller
Display
„ Refrigerant shortage or refrigerant system clogging (incorrect piping)
Supposed Causes
„ Defect of pressure sensor
„ Defect of outdoor unit PC board
Troubleshooting
522
Be sure to turn off power switch before connect or disconnect connector,
Caution or parts damage may be occurred.
YES
Cooling
NO
The suction
YES
pipe temperature minus
coil temperature is 20 ˚C
or higher.
NO
Resistance
is normal when
measured with the suction
NO
pipe thermistor (R4T) and
coil thermistor (R2T)
disconnected
from the outdoor
unit PC
board.
YES
Low pressure
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
Troubleshooting UM Combination "MA1R Series" Using R-407C
PACD011001C2
YES
Refrigerant shortage or refrigerant
system is clogged. Requires check
of refrigerant system.
YES
Replace low outdoor unit PC
board.
Replace low pressure sensor.
Refrigerant shortage or refrigerant
system is clogged. Requires
check of refrigerant system.
Replace the thermistor.
Replace the outdoor unit PC
board (A1P).
(VF052)