Outdoor Heat Exchanger Temperature Sensor Anomaly - Mitsubishi Heavy Industries FDT71VNXWVH Service Manual

Error code
Indoor control PCB
Remote control:
E37
Outdoor control PCB
Outdoor inverter
1. Applicable model
2. Error detection method
Detection of anomalously low
temperature (resistance) on
the outdoor heat exchanger
temperature sensor
3. Condition of error displayed
• When the temperature sensor
detects -50°C or lower for 20
seconds continuously within 2
minutes to 2 minutes 20 seconds
after the compressor ON, the
compressor stops. After 3-minutes
delay, the compressor starts again
automatically, but if this anomalous
temperature is detected 3 times
within 40 minutes.
• When -50°C or lower is detected for 5
seconds continuously within 20 seconds
after compressor ON.
4. Presumable cause
• Defective outdoor unit control
(or main) PCB
• Broken sensor harness or
temperature sensing section
• Disconnected wire connection
(connector)
Note:
LED Green
Keeps flashing
Keeps flashing
Yellow LED
PCB
Keeps flashing
5. Troubleshooting
Is the
outdoor heat
exchanger temperature
sensor connector
connected
properly?
YES
Are the
characteristics of
outdoor heat exchanger
temperature
sensor
OK?
Temperature-resistance characteristics
(Broken wire)
15
10
5
(Short-circuit)
Red
Content
Stays OFF
exchanger temperature
1-time flash
Diagnosis
NO
For the characteristics of outdoor heat exchanger
temperature sensor, see the following graph.
NO
YES
0 10 20 30 40 50
Temperature (°C)
102
- -
'19 • PAC-SM-332
Outdoor heat
sensor anomaly
Countermeasure
Correct connector.
Defective outdoor heat
exchanger temperature
sensor ➞ Replace.
Defective outdoor
unit control (or main)
PCB ➞ Replace.
(Defective outdoor heat
exchanger temperature
sensor input circuit)