Daikin RXYQ-TA Series, Service Manual

Page: 273 / 337

SiUS341615E Troubleshooting by Error Code
Service Diagnosis 260
3.54 Refrigerant Shortage
Error Code
U0
Applicable
Models
All outdoor unit models
Method of Error
Detection
Detect refrigerant shortage according to a low pressure level or a difference in heat exchanger
temperature from the suction pipe.
Error Decision
Conditions
Low pressure becomes 0.1 MPa (14.5 psi) or less.
∗
Error is not determined. The unit continues the operation.
Supposed
Causes
„
Refrigerant shortage and refrigerant clogging (wrong piping)
„
Defective thermistor
„
Defective low pressure sensor
„
Defective outdoor unit main PCB
Troubleshooting
Note:
∗
1. Check the low pressure value by using pressure gauge in operation.
∗
2. Compare the actual measurement value by pressure sensor with the value by the pressure
gauge.
(To gain actual measurement value by pressure sensor, measure the voltage at the connector
[between (2)-(3)] and then convert the value into pressure.
)
Refer to page 292.
Refer to page 302.
Is the low
pressure 0.1 MPa
(14.5 psi) or less?
(
∗
1)
Is the
characteristics of
low pressure sensor
normal? (
∗
2)
Replace the low pressure
sensor (S1NPL).
Replace the outdoor unit
main PCB (A1P).
NO NO
YES YES
Remove the factor of
decreasing low pressure.
CHECK 2
Caution
Be sure to turn off the power switch before connecting or disconnecting
connectors, or parts may be damaged.
(1)Mount a pressure gauge at the service port on the low
pressure side.
(2)Reset the operation using the remote controller then restart.
CHECK 12
CHECK 2
CHECK 12