Panasonic CU-3E19RBU-5 Service Manual page 71

15.2.6 H28 (Outdoor Heat Exchanger Temperature Sensor 1 Abnormality)
Malfunction Decision Conditions

During startup and operation of cooling and heating, the temperatures detected by the outdoor pipe temperature
sensor are used to determine sensor errors.
Malfunction Caused

Faulty connector connection.

Faulty sensor.

Faulty PCB.
Abnormality Judgment:

Continue for 5 seconds.
Troubleshooting
Sensor (Thermistor)
Characteristics
70
1
Outdoor Air Sensor
2
Outdoor Heat Exchanger
60
Sensor
50
40
1
30
2
20
10
0
-10 0 10 20 30
(14) (32) (50) (68) (86)
Temperature °C (°F)
Caution
Check the connector connection:
- Turn off the power
- Check the connector connection
Is the connector
connection normal?
Check the outdoor pipe temperature sensor:
- Plug out connector from the outdoor unit PCB
- Measure the resistance of the outdoor pipe
temperature sensor
Is the measured resistance of the
outdoor pipe temperature sensor
matches the value specified in its
characteristic chart?
40 50
(104) (122)
For safety reason and to prevent component
breakdown, always switch off the power before
remove and connect the component.
No
Yes
No
Yes
71
- Connector poor contact
- Correct the connection
- Defect in outdoor pipe
temperature sensor
- Replace the outdoor pipe
temperature sensor
-
Defect in outdoor unit PCB
- Replace the outdoor unit PCB