Outdoor Heat Exchanger Temperature Sensor Anomaly - Mitsubishi Heavy Industries FDT100VNAWVH Service Manual

Error code
Remote control:
E37
Indoor unit
control PCB
Outdoor unit
control PCB
1. Applicable model
All models
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-minute
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 second
after compressor ON.
4. Presumable cause
• Defective outdoor unit main
PCB
• Broken sensor harness or
temperature sensing section
• Disconnected wire connection
(connector)
Note:
LED Green
Keeps flashing
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
exchanger temperature
Stays OFF
1-time flash
Diagnosis
NO
For the characteristics of outdoor heat exchanger
temperature sensor, see the following graph.
NO
YES
5k at 25°C
0 10 20 30 40 50
Temperature (°C)
115
- -
'19 • PAC-SM-309
Outdoor heat
sensor anomaly
Countermeasure
Correct connector.
Defective outdoor heat
exchanger temperature
sensor ➞ Replace.
Defective outdoor unit main
PCB ➞ Replace.
(Defective outdoor heat
exchanger temperature
sensor input circuit)